Language：Japanese   Publishing type：Research paper (scientific journal)  

バングラデシュ産在来イネコレクション 135 系統を 材料として , 葉身の萎凋度 , 葉鞘におけるミネラル含 量, 溢液について定量的な耐塩性評価を行った. 各指 標についてコレクション内で品種間差が認められた . 葉身の萎凋度については , 大半の品種で葉身全体にお ける萎凋部位の割合が漸進的に増大したのに対し , 一 部の極感受性品種では塩ストレス処理開始後 , 短期間 で急激に萎凋が進んだ . 本手法により明らかにされた 塩ストレス耐性品種では葉鞘における Na, Mg, Ca 蓄積 の抑制がみられ , 塩ストレス感受性品種では溢液の量 が多い傾向にあった. 本研究において用いられた耐塩 性の定量的な評価法をもちいてバングラデシュ産在来 イネコレクションの耐塩性を評価し , 選抜された耐塩 性系統をもちいてイネ耐塩性に関する詳細な遺伝解析
が進展することが期待される .

DOI： 10.3390/plants10040725

Language：English   Publishing type：Research paper (scientific journal)  

The green rice leafhopper (GRH, Nephotettix cincticeps Uhler) is a serious insect pest of rice (Oryza sativa L.) in temperate regions of Asia. Wild Oryza species are the main source of resistance to insects. The W1413 accession of African wild rice (O. longistaminata A. Chev. & Roehrich) is resistant to GRH. To analyze its resistance, we developed 28 BC₃F₃ introgression lines carrying W1413 segments in the genetic background of Nipponbare, a susceptible rice cultivar, and evaluated their GRH resistance. Five BC₃F₃ populations were used for quantitative trait locus (QTL) analysis and seven BC₃F₄ populations for QTL validation. Four significant QTLs on the long arm of chromosome 2 (qGRH2), short arm of chromosome 4 (qGRH4), short arm of chromosome 5 (qGRH5), and long arm of chromosome 11 (qGRH11) were identified. The contribution of the W1413 allele at qGRH11 was the largest among the four QTLs; the other QTLs also contributed to GRH resistance. Chromosomal locations suggested that qGRH11 corresponds to the previously reported GRH resistance gene Grh2, qGRH4 to Grh6, and qGRH5 to Grh1. qGRH2 is a novel QTL for resistance to GRH. Thus, resistance of O. longistaminata to GRH can be explained by at least four QTLs.

DOI： 10.1270/jsbbs.19060

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/nph.14290

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.4236/ajps.2017.82018

Language：English   Publishing type：Research paper (scientific journal)  

DOI： Plant Sci.

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/srep05872

Language：English   Publishing type：Research paper (scientific journal)  

DOI： DOI: 10.1111/eea.12149

Language：English   Publishing type：Research paper (scientific journal)  

In this study, we developed the first genetic linkage map for the major rice insect pest, the brown planthopper (BPH, Nilaparvata lugens). The linkage map was constructed by integrating linkage data from two backcross populations derived from three inbred BPH strains. The consensus map consists of 474 simple sequence repeats, 43 single-nucleotide polymorphisms, and 1 sequence-tagged site, for a total of 518 markers at 472 unique positions in 17 linkage groups. The linkage groups cover 1093.9 cM, with an average distance of 2.3 cM between loci. The average number of marker loci per linkage group was 27.8. The sex-linkage group was identified by exploiting X-linked and Y-specific markers. Our linkage map and the newly developed markers used to create it constitute an essential re- source and a useful framework for future genetic analyses in BPH.
Key words: Nilaparvata lugens; brown planthopper; genetic linkage map; SSR; SNP

DOI： doi:10.1093/dnares/dss030

Language：English   Publishing type：Research paper (scientific journal)  

The brown planthopper (BPH), Nilaparvata 11 lugens(Sta ̊l),isoneofthemostseriousanddestructive 12 pests of rice, and can be found throughout the rice-growing 13 areas of Asia. To date, more than 24 major BPH-resistance 14 genes have been reported in several Oryza sativa ssp. 15 indica cultivars and wild relatives. Here, we report the 16 genetic basis of the high level of BPH resistance derived 17 from an Indian rice cultivar, ADR52, which was previously 18 identified as resistant to the whitebacked planthopper 19 (Sogatella furcifera [Horva ́th]). An F2 population derived 20 from a cross between ADR52 and a susceptible cultivar, 21 Taichung 65 (T65), was used for quantitative trait locus 22 (QTL) analysis. Antibiosis testing showed that multiple 23 loci controlled the high level of BPH resistance in this F2 24 population. Further linkage analysis using backcross pop- 25 ulations resulted in the identification of BPH-resistance 26 (antibiosis) gene loci from ADR52. BPH25 co-segregated 27 with marker S00310 on the distal end of the short arm of
A1 Communicated by T. Tai.
A2 K. K. M. Myint and D. Fujita contributed equally to this work.
A3 K. K. M. Myint

DOI： DOI 10.1007/s00122-011-1723-4

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1023/A:1026018821472

Publisher：Plant Production Science  

Genetic variation in heading dates is essential for developing a rational rice cultivation program, optimizing irrigation practices, and advancing plant breeding in year-round irrigated environments. In this study, we investigated the heading dates of eight rice varieties with varying degrees of photoperiod sensitivity under natural field conditions by conducting year-round periodic sowing in 2019 in Nay Pyi Taw, located in the central region of Myanmar. We elucidated genetic differences in critical day length by observing the longest day length at 30 days before heading, which is likely to be the starting point for floral induction. We analyzed two phenological models: the conventional developmental rate (DVR) model and a modified model considering the critical day length. These analyses aimed to uncover the genetic differences in phenological parameters: temperature sensitivity, photoperiod sensitivity, and earliness among rice varieties. Incorporating the critical day length into the DVR model significantly improved its accuracy in predicting heading dates, particularly for photoperiod-sensitive rice varieties. The parameters derived from the 2019 data proved effective for predicting heading dates in 2018, especially for photoperiod-sensitive varieties. The genetic variation in critical day length and model parameters could be valuable for adapting rice cultivars to different seasons and determining yield and agronomic practices for varietal development programs. These findings contribute to a deeper understanding of rice phenology and the genetic basis for photoperiod sensitivity in Myanmar rice.

DOI： 10.1080/1343943X.2024.2308336

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Paw San Hmwe (PSH) is an indigenous rice variety from Myanmar with a good taste, a pleasant fragrance, and excellent elongation ability during cooking. However, its low yield potential and strong photoperiod sensitivity reduce its productivity, and it is vulnerable to climate changes during growth. To improve the photoperiod insensitivity, yield, and plant stature of PSH, the high-yield genes Grain number 1a (Gn1a) and Wealthy Farmer’s Panicle (WFP), together with the photoperiod insensitivity trait, were introgressed into PSH via marker-assisted backcross breeding and phenotype selection. For the photoperiod insensitivity trait, phenotypic selection was performed under long-day conditions during the dry season. After foreground selection of Gn1a and WFP via simple sequence repeat genotyping, genotyping-by-sequencing was conducted to validate the introgression of target genes and determine the recurrent parent genome recovery of the selected lines. The improved lines were insensitive to photoperiod, and the Gn1a and WFP introgression lines showed significantly higher numbers of primary panicle branches and spikelets per panicle than the recurrent parent, with comparative similarity in cooking and eating qualities. This study successfully improved PSH by decreasing its photoperiod sensitivity and introducing high-yield genes via marker-assisted selection. The developed lines can be used for crop rotation and double-season cropping of better-quality rice.

Language：English   Publisher：Japanese Society of Breeding  

<p>The awn is a bristle-like appendage that protrudes from the seed tip and plays a critical role in preventing feed damage and spreading habitats in many grass species, including rice. While all wild species in the <i>Oryza</i> genus have awns, this trait has been eliminated in domesticated species due to its obstructive nature to agricultural processes. To date, several genes involved in awn development have been identified in wild rice, <i>Oryza rufipogon</i> and <i>Oryza barthii</i> which are ancestral species of cultivated rice in Asia and Africa, respectively. However, the responsible genes for awn development have not been identified in other wild rice species even though multiple QTLs have been reported previously. In this study, we identified <i>An7</i> gene responsible for awn development in two wild rice species, <i>Oryza glumaepatula</i> and <i>Oryza meridionalis</i>. <i>An7</i> encodes a cytochrome P450 enzyme and is homologous to <i>D2/CYP90D2</i>, a known brassinosteroid biosynthesis enzyme in rice. The identification of <i>An7</i> provides insight into a distinct molecular mechanism underlying awn development that occurs in geographically separated environments.</p>

DOI： 10.1270/jsbbs.23052

Web of Science

Scopus

PubMed

CiNii Research

Language：English   Publisher：Proceedings of the National Academy of Sciences of the United States of America  

Two species of rice have been independently domesticated from different ancestral wild species in Asia and Africa. Comparison of mutations that underlie phenotypic and physiological alterations associated with domestication traits in these species gives insights into the domestication history of rice in both regions. Asian cultivated rice, Oryza sativa, and African cultivated rice, Oryza glaberrima, have been modified and improved for common traits beneficial for humans, including erect plant architecture, nonshattering seeds, nonpigmented pericarp, and lack of awns. Independent mutations in orthologous genes associated with these traits have been documented in the two cultivated species. Contrary to this prevailing model, selection for awnlessness targeted different genes in O. sativa and O. glaberrima. We identify Regulator of Awn Elongation 3 (RAE3) a gene that encodes an E3 ubiquitin ligase and is responsible for the awnless phenotype only in O. glaberrima. A 48-bp deletion may disrupt the substrate recognition domain in RAE3 and diminish awn elongation. Sequencing analysis demonstrated low nucleotide diversity in a ~600-kb region around the derived rae3 allele on chromosome 6 in O. glaberrima compared with its wild progenitor. Identification of RAE3 sheds light on the molecular mechanism underlying awn development and provides an example of how selection on different genes can confer the same domestication phenotype in Asian and African rice.

DOI： 10.1073/pnas.2207105120

Web of Science

Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

Genetic variation in heading dates is essential for developing a rational rice cultivation program, optimizing irrigation practices, and advancing plant breeding in year-round irrigated environments. In this study, we investigated the heading dates of eight rice varieties with varying degrees of photoperiod sensitivity under natural field conditions by conducting year-round periodic sowing in 2019 in Nay Pyi Taw, located in the central region of Myanmar. We elucidated genetic differences in critical day length by observing the longest day length at 30 days before heading, which is likely to be the starting point for floral induction. We analyzed two phenological models: the conventional developmental rate (DVR) model and a modified model considering the critical day length. These analyses aimed to uncover the genetic differences in phenological parameters: temperature sensitivity, photoperiod sensitivity, and earliness among rice varieties. Incorporating the critical day length into the DVR model significantly improved its accuracy in predicting heading dates, particularly for photoperiod-sensitive rice varieties. The parameters derived from the 2019 data proved effective for predicting heading dates in 2018, especially for photoperiod-sensitive varieties. The genetic variation in critical day length and model parameters could be valuable for adapting rice cultivars to different seasons and determining yield and agronomic practices for varietal development programs. These findings contribute to a deeper understanding of rice phenology and the genetic basis for photoperiod sensitivity in Myanmar rice.

Language：English   Publishing type：Research paper (scientific journal)  

Two species of rice have been independently domesticated from different ancestral wild species in Asia and Africa. Comparison of mutations that underlie phenotypic and physiological alterations associated with domestication traits in these species gives insights into the domestication history of rice in both regions. Asian cultivated rice, Oryza sativa, and African cultivated rice, Oryza glaberrima, have been modified and improved for common traits beneficial for humans, including erect plant architecture, nonshattering seeds, nonpigmented pericarp, and lack of awns. Independent mutations in orthologous genes associated with these traits have been documented in the two cultivated species. Contrary to this prevailing model, selection for awnlessness targeted different genes in O. sativa and O. glaberrima. We identify Regulator of Awn Elongation 3 (RAE3) a gene that encodes an E3 ubiquitin ligase and is responsible for the awnless phenotype only in O. glaberrima. A 48-bp deletion may disrupt the substrate recognition domain in RAE3 and diminish awn elongation. Sequencing analysis demonstrated low nucleotide diversity in a ~600-kb region around the derived rae3 allele on chromosome 6 in O. glaberrima compared with its wild progenitor. Identification of RAE3 sheds light on the molecular mechanism underlying awn development and provides an example of how selection on different genes can confer the same domestication phenotype in Asian and African rice.

DOI： DOI 10.1073/pnas.2207105120

Language：English   Publisher：Japanese Society of Breeding  

<p>The brown planthopper (BPH: <i>Nilaparvata lugens</i> Stål) is one of the most destructive insects in rice production. The use of host plant resistance has potential to reduce damage caused by BPH. The heat tolerance <i>japonica</i> rice ‘Sagabiyori’, with superior grain quality and high soluble starch in the stem, is highly susceptible to damage by BPH. Here, to enhance its BPH resistance, we developed seven near-isogenic lines (NILs) carrying <i>BPH2</i>, <i>BPH17-ptb</i>, <i>BPH32</i>, <i>BPH3</i>, <i>BPH17</i>, <i>BPH20</i>, and <i>BPH21</i> through marker-assisted selection and evaluated resistance to two BPH populations. Most lines were more resistant to the Hadano-1966 BPH population than Sagabiyori but were less effective against the highly virulent Koshi-2013 population. Nevertheless, in antixenosis tests, Koshi-2013 settled less on all NILs than on Sagabiyori. In addition, adult mortality and the percentage of fresh weight loss of lines carrying <i>BPH17</i> and <i>BPH3</i> indicated that these lines have higher resistance to Koshi-2013 than Sagabiyori. Current study revealed that BPH resistance of Sagabiyori became stronger by transferring <i>BPH3</i> and <i>BPH17</i> genes. Thus, <i>BPH3</i> and <i>BPH17</i> might be valuable for breeding programs to enhance BPH resistance of high grain quality rice varieties with heat tolerance.</p>

DOI： 10.1270/jsbbs.23017

Web of Science

Scopus

PubMed

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists  

<p> This study was conducted to estimate the effects of nitrogen fertilizer application at low, moderate, and high level on photosynthesis, embryo area, and grain yield of a rice giant embryo mutant line (MGE13) in comparison with the originated rice variety Mizuhochikara (Miz). As increasing nitrogen fertilizer application, photosynthetic rate in term of the carbon dioxide exchange rate (CER) increased at the tillering, heading, and dough-ripening stages in both rice genotypes. Especially at the heading stage, the increase of CER was much higher in MGE13 than that in Miz as increasing nitrogen fertilizer from low to high level. The embryo area at both the dough-ripening and harvesting stages increased more in MGE13 than in Miz as increasing nitrogen fertilizer application level. The embryo area was significantly correlated with CER at the heading stage and with the plant growth rate during the ripening stage in both rice genotypes. Grain yield was similar in MGE13 and in Miz under low and moderate nitrogen fertilizer levels, but it was much higher in MGE13 than in Miz under the high nitrogen level, mainly due to the greater CER at heading stage, the higher dry matter weight and the larger number of panicles per plant.</p>

DOI： 10.2525/ecb.60.109

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Wild rice species have long awns at their seed tips, but this trait has been lost through rice domestication. Awn loss mitigates harvest and seed storage; further, awnlessness increases the grain number and, subsequently, improves grain yield in Asian cultivated rice, highlighting the contribution of the loss of awn to modern rice agriculture. Therefore, identifying the genes regulating awn development would facilitate the elucidation of a part of the domestication process in rice and increase our understanding of the complex mechanism in awn morphogenesis. To identify the novel loci regulating awn development and understand the conservation of genes in other wild rice relatives belonging to the AA genome group, we analyzed the chromosome segment substitution lines (CSSL). In this study, we compared a number of CSSL sets derived by crossing wild rice species in the AA genome group with the cultivated species Oryza sativa ssp. japonica. Two loci on chromosomes 7 and 11 were newly discovered to be responsible for awn development. We also found wild relatives that were used as donor parents of the CSSLs carrying the functional alleles responsible for awn elongation, REGULATOR OF AWN ELONGATION 1 (RAE1) and RAE2. To understand the conserveness of RAE1 and RAE2 in wild rice relatives, we analyzed RAE1 and RAE2 sequences of 175 accessions among diverse AA genome species retrieved from the sequence read archive (SRA) database. Comparative sequence analysis demonstrated that most wild rice AA genome species maintained functional RAE1 and RAE2, whereas most Asian rice cultivars have lost either or both functions. In addition, some different loss-of-function alleles of RAE1 and RAE2 were found in Asian cultivated species. These findings suggest that different combinations of dysfunctional alleles of RAE1 and RAE2 were selected after the speciation of O. sativa, and that two-step loss of function in RAE1 and RAE2 contributed to awnlessness in Asian cultivated rice.

DOI： 10.3390/plants10040725

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1270/JSBBS.21034

Other Link： https://www.scopus.com/inward/record.uri?eid=2-s2.0-85122199465&doi=10.1270%2fJSBBS.21034&partnerID=40&md5=29ac357a37bb64da969bddfdf9ac2544

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1270/jsbbs.21005

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Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Hybrid breakdown, a form of postzygotic reproductive barrier, has been reported to hinder gene flow in many crosses between wild and cultivated rice. Here, the phenomenon of hybrid breakdown was observed as low-tillering (i.e., low tiller number) in some progeny of an interspecific cross produced in an attempt to introduce Oryza meridionalis Ng (W1625) chromosomal segments into Oryza sativa L. ssp. japonica “Taichung 65” (T65). Low-tillering lines were obtained in BC4-derived progeny from a cross between W1625 and “Taichung 65,” but the locus for low-tillering could not be mapped in segregating populations. As a second approach to map the locus for low-tillering, we analyzed an F2 population derived from a cross between the low-tillering lines and a high-yielding indica cultivar, “Takanari.” A major QTL for low-tillering, qLTN4, was detected between PCR-based markers MS10 and RM307 on the long arm of chromosome 4, with a LOD score of 15.6. The low-tillering phenotype was associated with weak growth and pale yellow phenotype; however, low-tillering plant had less reduction of grain fertility. In an F4 population (4896 plants), 563 recombinant plants were identified and the low-tillering locus was delimited to a 4.6-Mbp region between markers W1 and C5-indel3729. This region could not be further delimited because recombination is restricted in this region of qLTN4, which is near the centromere. Understanding the genetic basis of hybrid breakdown, including the low-tillering habit, will be important for improving varieties in rice breeding.

DOI： 10.3389/fpls.2021.633247

Language：English   Publishing type：Research paper (scientific journal)  

Front. Plant Sci., 26 January 2021 | https://doi.org/10.3389/fpls.2020.632420

DOI： 10.3389/fpls.2020.632420

Language：English   Publishing type：Research paper (scientific journal)  

In F1 hybrids of Oryza sativa (Asian rice) and Oryza glaberrima (African rice), heterozygosity leads to a complete gamete abortion because of allelic conflict at each of the 13 hybrid sterility (HS) loci. We systematically produced 19 plants from the F1 hybrids of both the rice species by the anther culture (AC) method. Five of the 19 interspecific hybrid plants were partially fertile and able to produce seeds. Unlike ordinal doubled haploid plants resulting from AC, these regenerated plants showed various ploidy levels (diploid to pentaploid) and different zygosities (completely homozygous, completely heterozygous, and a combination). These properties were attributable to meiotic anomalies in the interspecific hybrid F1 plants. Examination of the genetic structures of the regenerated plants suggested meiotic non-reduction took place in the interspecific hybrid F1 plants. The centromeric regions in the regenerated plants revealed that the abnormal first and/or second divisions of meiosis, namely the first division restitution (FDR) and/or second division restitution (SDR), had occurred in the interspecific hybrid. Immunohistochemical observations also verified these phenomena. FDR and SDR occurrences at meiosis might strongly lead to the formation of diploid microspores. The results demonstrated that meiotic anomalies functioned as a reproductive barrier occurred before the HS genes acted in gamete of the interspecific hybrid. Although such meiotic anomalies are detrimental to pollen development, the early rescue of microspores carrying the diploid gamete resulted in the fertile regenerated plants. The five partially fertile plants carrying tetraploid genomes with heterozygous alleles of the HS loci produced fertile diploid pollens, implying that the diploid gametes circumvented the allelic conflicts at the HS loci. We also proposed how diploid male gametes avoid HS with the killer–protector model.

DOI： 10.3389/fpls.2020.579305

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Language：English   Publishing type：Research paper (scientific journal)  

The brown planthopper (BPH: Nilaparvata lugens Stål.) is a major pest of rice, Oryza sativa, in Asia. Host plant resistance has tremendous potential to reduce the damage caused to rice by the planthopper. However, the effectiveness of resistance genes varies spatially and temporally according to BPH virulence. Understanding patterns in BPH virulence against resistance genes is necessary to efficiently and sustainably deploy resistant rice varieties. To survey BPH virulence patterns, seven near-isogenic lines (NILs), each with a single BPH resistance gene (BPH2-NIL, BPH3-NIL, BPH17-NIL, BPH20-NIL, BPH21-NIL, BPH32-NIL and BPH17-ptb-NIL) and fifteen pyramided lines (PYLs) carrying multiple resistance genes were developed with the genetic background of the japonica rice variety, Taichung 65 (T65), and assessed for resistance levels against two BPH populations (Hadano-66 and Koshi-2013 collected in Japan in 1966 and 2013, respectively). Many of the NILs and PYLs were resistant against the Hadano-66 population but were less effective against the Koshi-2013 population. Among PYLs, BPH20+BPH32-PYL and BPH2+BPH3+BPH17-PYL granted relatively high BPH resistance against Koshi-2013. The NILs and PYLs developed in this research will be useful to monitor BPH virulence prior to deploying resistant rice varieties and improve rice’s resistance to BPH in the context of regionally increasing levels of virulence.

DOI： 10.3390/plants8110498

Language：English   Publishing type：Research paper (scientific journal)  

Life histories and breeding systems strongly affect the genetic diversity of seed plants, but the genetic architectures that promote outcrossing in Oryza longistaminata, a perennial wild species in Africa, are not understood. We conducted a genetic analysis of the anther length of O. longistaminata accession W1508 using advanced backcross quantitative trait locus (QTL) analysis and chromosomal segment substitution lines (CSSLs) in the genetic background of O. sativa Taichung 65 (T65), with simple sequence repeat markers. QTL analysis of the BC₃F₁ population (n = 100) revealed that four main QTL regions on chromosomes 3, 5, and 6 were associated to anther length. We selected a minimum set of BC₃F₂ plants for the development of CSSLs to cover as much of the W1508 genome as possible. The additional minor QTLs were suggested in the regional QTL analysis, using 21 to 24 plants in each of the selected BC₃F₂ population. The main QTLs found on chromosomes 3, 5, and 6 were validated and designated qATL3, qATL5, qATL6.1, and qATL6.2, as novel QTLs identified in O. longistaminata in the mapping populations of 94, 88, 70, and 95 BC3F4 plants. qATL3, qATL5, and qATL6.1 likely contributed to anther length by cell elongation, whereas qATL6.2 likely contributed by cell multiplication. The QTLs were confirmed again in an evaluation of the W1508ILs. In several chromosome segment substitution lines without the four validated QTLs, the anthers were also longer than those of T65, suggesting that other QTLs also increase anther length in W1508. The cloning and diversity analyses of genes conferring anther length QTLs promotes utilization of the genetic resources of wild species, and the understanding of haplotype evolution on the differentiation of annuality and perenniality in the genus Oryza.

DOI： 10.3390/plants8100388

Language：English   Publishing type：Research paper (scientific journal)  

To evaluate and utilize potentially valuable quantitative trait loci or genes of wild relatives in the genetic background of domesticated crop species, chromosome segment substitution lines (CSSLs) are a valuable tool. CSSLs can be constructed through the exchange of chromosome segments of AA genome species of the genus Oryza with cultivated rice, Oryza sativa L. Here we report the development of three sets of CSSLs carrying segments of AA genome species closely related to Oryza sativa—O. glaberrima (IRGC 103777 from Mali), O. rufipogon (W1962 from China), and O. nivara (IRGC 105715 from Cambodia)—in the genetic background of ssp. japonica cultivar Taichung 65 through the use of 101 to 121 simple-sequence-repeat markers in whole-genome genotyping and marker-assisted selection. The materials are available via the National Bioresource Project (Rice) Oryzabase Web page.

DOI： 10.3390/plants8100388

Language：English   Publishing type：Research paper (scientific journal)  

The brown planthopper (BPH: Nilaparvata lugens Stål.) is a major pest of rice, Oryza sativa, in Asia. Host plant resistance has tremendous potential to reduce the damage caused to rice by the planthopper. However, the effectiveness of resistance genes varies spatially and temporally according to BPH virulence. Understanding patterns in BPH virulence against resistance genes is necessary to efficiently and sustainably deploy resistant rice varieties. To survey BPH virulence patterns, seven near-isogenic lines (NILs), each with a single BPH resistance gene (BPH2-NIL, BPH3-NIL, BPH17-NIL, BPH20-NIL, BPH21-NIL, BPH32-NIL and BPH17-ptb-NIL) and fifteen pyramided lines (PYLs) carrying multiple resistance genes were developed with the genetic background of the japonica rice variety, Taichung 65 (T65), and assessed for resistance levels against two BPH populations (Hadano-66 and Koshi-2013 collected in Japan in 1966 and 2013, respectively). Many of the NILs and PYLs were resistant against the Hadano-66 population but were less effective against the Koshi-2013 population. Among PYLs, BPH20+BPH32-PYL and BPH2+BPH3+BPH17-PYL granted relatively high BPH resistance against Koshi-2013. The NILs and PYLs developed in this research will be useful to monitor BPH virulence prior to deploying resistant rice varieties and improve rice’s resistance to BPH in the context of regionally increasing levels of virulence.

DOI： 10.3390/plants8110498

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The green rice leafhopper (GRH), Nephotettix cincticeps Uhler, is a major insect pest of cultivated rice, Oryza sativa L., throughout the temperate regions of East Asia. GRH resistance had been reported in the wild species Oryza nivara but genetic basis of GRH resistance in wild rice accession has not been clarified. Here, we found a major QTL, qGRH4.2, on chromosome 4 conferred GRH resistance with 14.1 of the logarithm of odds (LOD) score explaining 67.6% of phenotypic variance in the BC₁F₁ population derived from a cross between the susceptible japonica cultivar ‘Taichung 65’ (T65) and O. nivara accession IRGC105715. qGRH4.2 has been identified as GRH6 between the markers RM5414 and C60248 in a BC₃F₂ population derived from two BC₃F₁ plants resistant to GRH. In a high-resolution mapping, the GRH6 region was delimited between the markers G6-c60k and 7L16f, and corresponded to an 31.2-kbp region of the ‘Nipponbare’ genome. Understanding the genetic basis of GRH resistance will facilitate the use of GRH resistance genes in marker-assisted breeding in rice.

DOI： 10.1270/jsbbs.19029

Language：English   Publishing type：Research paper (scientific journal)  

To evaluate and utilize potentially valuable quantitative trait loci or genes of wild relatives in the genetic background of domesticated crop species, chromosome segment substitution lines (CSSLs) are a valuable tool. CSSLs can be constructed through the exchange of chromosome segments of AA genome species of the genus Oryza with cultivated rice, Oryza sativa L. Here we report the development of three sets of CSSLs carrying segments of AA genome species closely related to Oryza sativa—O. glaberrima (IRGC 103777 from Mali), O. rufipogon (W1962 from China), and O. nivara (IRGC 105715 from Cambodia)—in the genetic background of ssp. japonica cultivar Taichung 65 through the use of 101 to 121 simple-sequence-repeat markers in whole-genome genotyping and marker-assisted selection. The materials are available via the National Bioresource Project (Rice) Oryzabase Web page.

DOI： 10.1270/jsbbs.19002

Language：English   Publishing type：Research paper (scientific journal)  

We tested the hypotheses that increasing the number of anti-herbivore resistance loci in crop plants will increase resistance strength, increase the spectrum of resistance (the number of species affected), and increase resistance stability. We further examined the potential ecological costs of pyramiding resistance under benign environments. In our experiments, we used 14 near-isogenic rice lines with zero (T65: recurrent parent), one, two or three resistance loci introgressed through marker-assisted selection. Lines with two or more loci that were originally bred for resistance to the green rice leafhopper, Nephotettix cincticeps, significantly reduced egg-laying by the green leafhopper, N. virescens. Declines in egg-number and in nymph weight were correlated with the numbers of resistance loci in the rice lines. To test the spectrum of resistance, we challenged the lines with a range of phloem feeders including the zig-zag leafhopper, Recilia dorsalis, brown planthopper, Nilaparvata lugens, and whitebacked planthopper, Sogatella furcifera. There was an increase in the number of tested species showing significant declines in egg-laying and nymph survival on lines with increasing numbers of loci. In a screen house trial that varied rates of nitrogenous fertilizer, a line with three loci had stable resistance against the green leafhopper and the grain yields of infested plants were maintained or increased (overcompensation). Under benign conditions, plant growth and grain yields declined with increasing numbers of resistance loci. However, under field conditions with natural exposure to herbivores, there were no significant differences in final yields. Our results clearly indicate the benefits, including unanticipated benefits such as providing resistance against multiple herbivore species, of pyramiding anti-herbivore resistance genes/loci in crop plants. We discuss our results as part of a review of existing research on pyramided resistance against leafhoppers and planthoppers in rice. We suggest that potential ecological costs may be overcome by the careful selection of gene combinations for pyramiding, avoidance of high (potentially redundant) loci numbers, and introgression of loci into robust plant types such as hybrid rice varieties.

DOI： 10.1016/j.cropro.2018.09.013

Language：English   Publishing type：Research paper (scientific journal)  

Background: To investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima). Male gametes of these hybrids display complete sterility owing to a dozen of hybrid sterility loci, termed HS loci, but this complicated genetic system remains poorly understood. Results: Microspores from these interspecific hybrids form sterile pollen but are viable at the immature stage. Application of the anther culture (AC) method caused these immature microspores to induce callus. The segregation distortion of 11 among 13 known HS loci was assessed in the callus population. Using many individual calli, fine mapping of the HS loci was attempted based on heterozygotes produced from chromosome segment substitution lines (CSSLs). Transmission ratio distortion (TRD) from microspores was detected at 6 of 11 HS loci in the callus population. The fine mapping of S ₁ and S ₁₉ loci using CSSLs revealed precise distances of markers from the positions of HS loci exhibiting excessive TRD. Conclusions: We demonstrated that AC to generate callus populations derived from immature microspores is a useful methodology for genetic study. The callus population facilitated detection of TRD at multiple HS loci and dramatically shortened the process for mapping hybrid sterility genes.

DOI： 10.1186/s13007-018-0370-z

Language：English   Publishing type：Research paper (scientific journal)  

Pyramiding resistance genes is predicted to increase the durability of resistant rice varieties against phloem-feeding herbivores. We examined responses by the green leafhopper, Nephotettix virescens (Hemiptera: Cicadellidae), to near-isogenic rice lines with zero, one and two resistance genes. The recurrent parent (T65) and monogenic lines (GRH2-NIL and GRH4-NIL) with genes for resistance to the green rice leafhopper, Nephotettix cincticeps (Hemiptera: Cicadellidae), were susceptible to the green leafhopper, but the pyramided line (GRH2/GRH4-PYL) was highly resistant to the green leafhopper. We selected green leafhoppers, N. virescens, from five sites in the Philippines for over 20 generations on each of the four lines. Populations selected on GRH2/GRH4-PYL gained partial virulence (feeding and development equal to that on T65) to the pyramided line within 10 generations and complete virulence (egg-laying equal to that on T65) within 20 generations. After 20 generations of rearing on the susceptible monogenic lines, green leafhoppers were also capable of developing and laying eggs on GRH2/GRH4-PYL. Furthermore, green leafhoppers reared on the susceptible GRH4-NIL for 20 generations showed equal preferences for T65 and GRH2/GRH4-PYL in choice bioassays. Our results indicate that previous long-term exposure to ineffective genes (including unperceived resistance genes) could dramatically reduce the durability of pyramided resistance. We suggest that informed crop management and deployment strategies should be developed to accompany rice lines with pyramided resistance and avoid the build-up of virulent herbivore populations.

DOI： 10.1016/j.cropro.2018.07.010

Language：English  

DOI： 10.1007/978-981-10-7308-3_2

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/s12284-017-0158-1

Language：English   Publishing type：Research paper (scientific journal)  

Background: High water use efficiency is essential to water-saving cropping. Morphological traits that affect photosynthetic water use efficiency are not well known. We examined whether leaf hairiness improves photosynthetic water use efficiency in rice. Results: A chromosome segment introgression line (IL-hairy) of wild Oryza nivara (Acc. IRGC105715) with the genetic background of Oryza sativa cultivar ‘IR24’ had high leaf pubescence (hair). The leaf hairs developed along small vascular bundles. Linkage analysis in BC₅F₂ and F₃ populations showed that the trait was governed by a single gene, designated BLANKET LEAF (BKL), on chromosome 6. IL-hairy plants had a warmer leaf surface in sunlight, probably due to increased boundary layer resistance. They had a lower transpiration rate under moderate and high light intensities, resulting in higher photosynthetic water use efficiency. Conclusion: Introgression of BKL on chromosome 6 from O. nivara improved photosynthetic water use efficiency in the genetic background of IR24.

DOI： 10.1186/s12284-017-0158-1

Language：English   Publishing type：Research paper (scientific journal)  

To avoid low oxygen, oxygen deficiency or oxygen deprivation, deepwater rice cultivated in flood planes can develop elongated internodes in response to submergence. Knowledge of the gene regulatory networks underlying rapid internode elongation is important for an understanding of the evolution and adaptation of major crops in response to flooding. To elucidate the genetic and molecular basis controlling their deepwater response we used microarrays and performed expression quantitative trait loci (eQTL) and phenotypic QTL (phQTL) analyses of internode samples of 85 recombinant inbred line (RIL) populations of non-deepwater (Taichung 65)- and deepwater rice (Bhadua). After evaluating the phenotypic response of the RILs exposed to submergence, confirming the genotypes of the populations, and generating 188 genetic markers, we identified 10,047 significant eQTLs comprised of 2,902 cis-eQTLs and 7,145 trans-eQTLs and three significant eQTL hotspots on chromosomes 1, 4, and 12 that affect the expression of many genes. The hotspots on chromosomes 1 and 4 located at different position from phQTLs detected in this study and other previous studies. We then regarded the eQTL hotspots as key regulatory points to infer causal regulatory networks of deepwater response including rapid internode elongation. Our results suggest that the downstream regulation of the eQTL hotspots on chromosomes 1 and 4 is independent, and that the target genes are partially regulated by SNORKEL1 and SNORKEL2 genes (SK1/2), key ethylene response factors. Subsequent bioinformatic analyses, including gene ontology-based annotation and functional enrichment analysis and promoter enrichment analysis, contribute to enhance our understanding of SK1/2-dependent and independent pathways. One remarkable observation is that the functional categories related to photosynthesis and light signaling are significantly over-represented in the candidate target genes of SK1/2. The combined results of these investigations together with genetical genomics approaches using structured populations with a deepwater response are also discussed in the context of current molecular models concerning the rapid internode elongation in deepwater rice. This study provides new insights into the underlying genetic architecture of gene expression regulating the response to flooding in deepwater rice and will be an important community resource for analyses on the genetic basis of deepwater responses.

DOI： 10.3389/fpls.2017.01753

Language：English   Publishing type：Research paper (scientific journal)  

When rice is grown under moderate salinity (6 dS m⁻¹), yields are reduced by up to 50%. The development of salt-tolerant varieties is a key strategy for increasing yields. We conducted an experiment using a hydroponic system with ion components similar to seawater to determine useful parameters for assessing salt tolerance. Two-week-old seedlings were grown for 7 days on Yoshida hydroponic solution. The treatment group then additionally received an artificial seawater solution (electrical conductivity, 12 dS m⁻¹). After a 2-week period of salt stress, standard evaluation scores (SES) of visual salt injuries were assessed. The K, Na, Mg, and Ca contents were then determined in the roots, sheaths, and leaves of each plant. Following the SES results, we divided the 37 genotypes into four groups: salt-tolerant groups (STGs), moderately salt-tolerant groups, salt-sensitive groups (HSSGs), and highly salt-sensitive groups (HSSGs). In the control, STGs had the highest sheath K content (30.1 mg g⁻¹ dried weight [DW]), whereas HSSGs had the lowest (21.4 mg g⁻¹ DW). Sheath K was also highly and negatively correlated with SES. This suggests that sheath K may be useful for identifying salt-tolerant varieties under non-saline conditions. Plant growth was significantly affected under salt stress, but STGs had the smallest decrease in sheath DW. SES was significantly correlated with sheath and leaf Na, sheath K and Mg, and sheath and leaf Na/K and Na/Mg ratios. The results suggested that sheath K, Na/K, and Na/Mg may be useful indicators for genetic analyses of salt-tolerant varieties under salt-stress conditions. The salt-tolerant cultivars, KCR20, KCR124, and KCR136, are possible candidates for such studies because they had high sheath K content (31.19, 31.21, 29.44 mg g⁻¹ DW, respectively) under non-saline conditions and low SES (3.3, 3.6, 3.9, respectively), and low sheath Na/K (0.64, 0.52, 0.92, respectively) and Na/Mg ratios (2.96, 2.27, 3.03, respectively) under salt-stress conditions.

DOI： 10.1080/00380768.2017.1323672

Language：English   Publishing type：Research paper (scientific journal)  

Reproductive barriers are commonly observed in both animals and plants, in which they maintain species integrity and contribute to speciation. This report shows that a combination of loss-offunction alleles at two duplicated loci, DUPLICATED GAMETOPHYTIC STERILITY 1 (DGS1) on chromosome 4 and DGS2 on chromosome 7, causes pollen sterility in hybrid progeny derived from an interspecific cross between cultivated rice, Oryza sativa, and an Asian annual wild rice, O. nivara. Male gametes carrying the DGS1 allele from O. nivara (DGS1-nivara^s) and the DGS2 allele from O. sativa (DGS2-T65^s) were sterile, but female gametes carrying the same genotype were fertile. We isolated the causal gene, which encodes a protein homologous to DNA-dependent RNA polymerase (RNAP) III subunit C4 (RPC4). RPC4 facilitates the transcription of 5S rRNAs and tRNAs. The loss-of-function alleles at DGS1-nivara^s and DGS2-T65^s were caused by weak or nonexpression of RPC4 and an absence of RPC4, respectively. Phylogenetic analysis demonstrated that gene duplication of RPC4 at DGS1 and DGS2 was a recent event that occurred after divergence of the ancestral population of Oryza from other Poaceae or during diversification of AA-genome species.

DOI： 10.1534/g3.117.043943

Language：English   Publishing type：Research paper (scientific journal)  

Domestication of crops based on artificial selection has contributed numerous beneficial traits for agriculture. Wild characteristics such as red pericarp and seed shattering were lost in both Asian (Oryza sativa) and African (Oryza glaberrima) cultivated rice species as a result of human selection on common genes. Awnedness, in contrast, is a trait that has been lost in both cultivated species due to selection on different sets of genes. In a previous report, we revealed that at least three loci regulate awn development in rice; however, the molecular mechanism underlying awnlessness remains unknown. Here we isolate and characterize a previously unidentified EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family member named REGULATOR OF AWN ELONGATION 2 (RAE2) and identify one of its requisite processing enzymes, SUBTILISIN-LIKE PROTEASE 1 (SLP1). The RAE2 precursor is specifically cleaved by SLP1 in the rice spikelet, where the mature RAE2 peptide subsequently induces awn elongation. Analysis of RAE2 sequence diversity identified a highly variable GC-rich region harboring multiple independent mutations underlying protein-length variation that disrupt the function of the RAE2 protein and condition the awnless phenotype in Asian rice. Cultivated African rice, on the other hand, retained the functional RAE2 allele despite its awnless phenotype. Our findings illuminate the molecular function of RAE2 in awn development and shed light on the independent domestication histories of Asian and African cultivated rice.

DOI： 10.1073/pnas.1604849113

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DNA marker-assisted selection (MAS) has become an indispensable component of breeding. Single nucleotide polymorphisms (SNP) are the most frequent polymorphism in the rice genome. However, SNP markers are not readily employed in MAS because of limitations in genotyping platforms. Here the authors report a Golden Gate SNP array that targets specific genes controlling yield-related traits and biotic stress resistance in rice. As a first step, the SNP genotypes were surveyed in 31 parental varieties using the Affymetrix Rice 44K SNP microarray. The haplotype information for 16 target genes was then converted to the Golden Gate platform with 143-plex markers. Haplotypes for the 14 useful allele are unique and can discriminate among all other varieties. The genotyping consistency between the Affymetrix microarray and the Golden Gate array was 92.8%, and the accuracy of the Golden Gate array was confirmed in 3 F₂ segregating populations. The concept of the haplotype-based selection by using the constructed SNP array was proofed.

DOI： 10.1016/j.plantsci.2015.09.008

Language：English   Publishing type：Research paper (scientific journal)  

The rice cultivar ASD7 (Oryza sativa L. ssp. indica) is resistant to the brown planthopper (BPH; Nilaparvata lugens Stål) and the green leafhopper (Nephotettix virescens Distant). Here, we analyzed multiple genetic resistance to BPH and the green rice leafhopper (GRH; Nephotettix cincticeps Uhler). Using two independent F₂ populations derived from a cross between ASD7 and Taichung 65 (Oryza sativa ssp. japonica), we detected two QTLs (qBPH6 and qBPH12) for resistance to BPH and one QTL (qGRH5) for resistance to GRH. Linkage analysis in BC₂F₃ populations revealed that qBPH12 controlled resistance to BPH and co-segregated with SSR markers RM28466 and RM7376 in plants homozygous for the ASD7 allele at qBPH6 Plants homozygous for the ASD7 alleles at both QTLs showed a much faster antibiosis response to BPH than plants homozygous at only one of these QTLs. It revealed that epistatic interaction between qBPH6 and qBPH12 is the basis of resistance to BPH in ASD7 In addition, qGRH5 controlled resistance to GRH and co-segregated with SSR markers RM6082 and RM3381. qGRH5 is identical to GRH1 Thus, we clarified the genetic basis of multiple resistance of ASD7 to BPH and GRH.

DOI： 10.1270/jsbbs.65.420

Language：English   Publishing type：Research paper (scientific journal)  

This study examines the resistance of recently developed near-isogenic rice lines (NILs) with BPH25 and BPH26 genes and the resistance donor cultivar ADR52 against Philippine populations of the brown planthopper, Nilaparvata lugens (Stål). Monogenic and pyramided lines with BPH25 and BPH26 were largely ineffective against the planthopper in a series of laboratory bioassays. In previous studies, BPH25 and a pyramided BPH25 + 26-NIL had been effective in reducing the fitness of N. lugens collected in Mindanao (Philippines); however, the virulence of the planthopper appears to have developed recently in Mindanao so the NILs are now ineffective. ADR52 showed marginal resistance against N. lugens, was more generally resistant against the white-backed planthopper, Sogatella furcifera (Horváth), and had strong resistance against the green leafhopper, Nephotettix virescens (Distant). Resistance against the latter two species was not derived from either BPH25 or BPH26, indicating that the cultivar possesses other resistance genes. For all three insect species, egg laying was constant on ADR52 as the plants aged; however, resistance against nymphs of all three insects increased as ADR52 aged. ADR52 had generally high tolerance against all three insects, which increased under high nitrogen conditions. The results of this study indicate ADR52 is a potential source of further resistance genes against leafhoppers and planthoppers. However, the results also indicate the need to carefully manage resistance genes to avoid adaptation by target insects as has occurred with BPH25 and BPH26.

DOI： 10.1007/s13355-015-0364-5

Language：English   Publishing type：Research paper (scientific journal)  

fonfers enhanced resistance to green rice leafhoppers (GRH), Nephotettix cincticeps Uhler. A pyramided line carrying GRH2 and GRH4 (TGRH29) showed strong resistance to GRH insects compared with a GRH2 near-isogenic line (TGRH11), although GRH4 alone did not confer any resistance to GRH. To explore the effects of GRH2 and GRH4 on GRH resistance, we investigated the transcriptional response of rice plants to GRH infestation using DNA microarray analysis. The expression of a large number of genes encoding pathogenesis-related proteins, lipoxygenases, terpene synthase (TPS) and WRKY transcription factor, was upregulated in response to GRH infestation in TGRH11 and TGRH29 compared with control plants. Quantitative RT-PCR revealed that expression of JAmyb and TPS was more strongly and more rapidly upregulated in TGRH29 compared with TGRH11 after GRH infestation. These results suggest that TGRH29 plants can more rapidly and strongly activate the defense response compared with plants carrying GRH2 alone. Furthermore, sesquiterpenes were emitted from TGRH29 plants in response to attack by GRH. The strong induction of sesquiterpene production in the TGRH29 line was correlated with the transcript levels of TPS genes. Our results suggest that GRH2 and GRH4 activate various defense responses and confer strong GRH insect resistance.

DOI： 10.5511/plantbiotechnology.15.0615a

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

A long awn is one of the distinct morphological features of wild rice species. This organ is thought to aid in seed dispersal and prevent predation by animals. Most cultivated varieties of Oryza sativa and Oryza glaberrima, however, have lost the ability to form long awns. The causal genetic factors responsible for the loss of awn in these two rice species remain largely unknown. Here, we evaluated three sets of chromosome segment substitution lines (CSSLs) in a common O. sativa genetic background (cv. Koshihikari) that harbor genomic fragments from Oryza nivara, Oryza rufipogon, and Oryza glaberrima donors. Phenotypic analyses of these libraries revealed the existence of three genes, Regulator of Awn Elongation 1 (RAE1), RAE2, and RAE3, involved in the loss of long awns in cultivated rice. Donor segments at two of these genes, RAE1 and RAE2, induced long awn formation in the CSSLs whereas an O. sativa segment at RAE3 induced long awn formation in O. glaberrima. These results suggest that the two cultivated rice species, O. sativa and O. glaberrima, have taken independent paths to become awnless.

DOI： 10.1534/g3.115.020834

Language：English   Publishing type：Research paper (scientific journal)  

The green leafhopper, Nephotettix virescens (Distant) (Hemiptera: Cicadellidae), occasionally damages rice in Asia either directly, by feeding on the host phloem, or indirectly by transmitting tungro virus. We assessed the nature of resistance against the leafhopper in monogenic and pyramided near-isogenic rice lines containing the resistance genes Grh2 and Grh4. Only the pyramided line was resistant to leafhopper damage. Leafhopper nymphs and adults had high mortality and low weight gain when feeding on the pyramided line and adults laid few eggs. In contrast, although there was some minor resistance in 45-day-old plants that possessed either Grh2 or Grh4 genes, the monogenic lines were generally as susceptible to the leafhopper as the recurrent parent line Taichung65 (T65). Resistance in the pyramided line was stable as the plant aged and under high nitrogen, and affected each of five Philippine leafhopper populations equally. Furthermore, in a selection study, leafhoppers failed to adapt fully to the pyramided resistant line: nymph and adult survival did improve during the first five generations of selection and attained similar levels as on T65, but egg-laying failed to improve over 10 generations. Our preliminary results suggested that resistance was associated with physiological costs to the plants in some experiments. The results of this study demonstrate the success of pyramiding resistance genes through marker-assisted breeding, to achieve a strong and potentially durable resistance. We discuss the utility of gene pyramiding and the development of near-isogenic lines for leafhopper management.

DOI： 10.1111/eea.12149

Language：English   Publishing type：Research paper (scientific journal)  

Gibberellin (GA) is a plant hormone that has important roles in numerous plant developmental phases. Rice plants known as deepwater rice respond to flooding by elongating their internodes to avoid anoxia. Previous studies reported that GA is essential for internode elongation in deepwater rice. Quantitative trait locus (QTL) analyses identified QTLs regulating internode elongation in response to deepwater conditions. However, the interaction between internode elongation and regulators of GA sensitivity in deepwater rice is unknown. In this study, we applied GA to recombinant inbred lines of T65 (non-deepwater rice) and Bhadua (deepwater rice), and performed a QTL analysis of internode elongation in response to GA. GA-induced internode elongation was detected only in deepwater rice. Our QTL analysis revealed two major QTLs on chromosomes 3 and 9 regulating total internode length, lowest elongated internode and number of elongated internodes. Furthermore, the QTL on chromosome 3 acted as an enhancer of other QTLs (e.g. the QTL on chromosome 12). Nearly isogenic lines of deepwater rice carrying the QTL regions from chromosomes 3 and 12 of the deepwater rice C9285 showed internode elongation in response to GA. Thus, these QTLsmay regulate GA responsiveness in deepwater rice. This study furthers our understanding of the mechanism of internode elongation in rice.

DOI： 10.1093/aobpla/plu028

Language：English   Publishing type：Research paper (scientific journal)  

In this study, we developed the first genetic linkage map for the major rice insect pest, the brown planthopper (BPH, Nilaparvata lugens). The linkage map was constructed by integrating linkage data from two backcross populations derived from three inbred BPH strains. The consensus map consists of 474 simple sequence repeats, 43 single-nucleotide polymorphisms, and 1 sequence-tagged site, for a total of 518 markers at 472 unique positions in 17 linkage groups. The linkage groups cover 1093.9 cM, with an average distance of 2.3 cM between loci. The average number of marker loci per linkage group was 27.8. The sex-linkage group was identified by exploiting X-linked and Y-specific markers. Our linkage map and the newly developed markers used to create it constitute an essential resource and a useful framework for future genetic analyses in BPH.

DOI： 10.1093/dnares/dss030

Language：English   Publishing type：Research paper (scientific journal)  

Using backcross inbred lines (BILs) derived from a cross between temperate japonica rice cultivars, Moritawase and Koshihikari, we validated the major quantitative trait loci (QTL) for eating quality and textural characteristics on chromosomes (Chr) 1, 2, 3, 6, 7, 10, and 12. Signifcant genetic differences in eating quality among BILs were detected at the QTL on Chr 3 and corresponded to the differences between the parents. Although differences in eating quality on the other chromosomes were not signifcant by t-test, cluster analysis and principal component analysis clearly showed that the genetic effects of the QTLs on Chr 6, 7, and 10 were similar to that on Chr 3, but the genetic effects of QTLs on Chr 1, 2, and 12 were entirely different from that on Chr 3. We previously identified that textural characteristics were highly correlated with eating quality. In this study, genetic differences in textural characteristics were similar to the genetic differences in eating quality among BILs. These results reveal major QTLs for eating quality of Koshihikari on Chr 3, 6, 7, and 10. The QTL on Chr 3 contributed most to the improvement of eating quality and textural characteristics.

DOI： 10.1626/pps.16.131

Language：English   Publishing type：Research paper (scientific journal)  

Deepwater rice possesses internode elongation ability to avoid drowning under deepwater conditions. Previous studies identified three QTLs regulating internode elongation ability on chromosomes 1, 3 and 12 using different populations. However, these QTLs only induce internode elongation in response to deepwater conditions from the 7-leaf stage and not during the early leaf stage. In this study, we detected two novel QTLs, qTIL2 and qTIL4 regulating deepwater response at the early leaf stage using an F₂ population derived from the cross between NIL1-3-12 carrying the three QTLs regulating deepwater response in T65 (O. sativa ssp. japonica) genetic background and C9285 (O. sativa ssp. indica, deepwater rice). Plants of the BC₂F₂ population derived from NIL1-3-12/C9285 and the RILs of T65/Bhadua (O. sativa ssp. indica, deepwater rice) possessing these QTLs as well as the three QTLs previously identified also showed internode elongation during the early leaf stage. These results indicate that qTIL2 and qTIL4 regulate early internode elongation and function in coordination with the three major QTLs under deepwater conditions. The results presented here would not only help define the mechanism of deepwater response in rice but also contribute in the breeding of deepwater tolerant rice that is adapted to various water depths.

DOI： 10.1270/jsbbs.62.178

Language：English   Publishing type：Research paper (scientific journal)  

The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the most serious and destructive pests of rice, and can be found throughout the rice-growing areas of Asia. To date, more than 24 major BPH-resistance genes have been reported in several Oryza sativa ssp. indica cultivars and wild relatives. Here, we report the genetic basis of the high level of BPH resistance derived from an Indian rice cultivar, ADR52, which was previously identified as resistant to the whitebacked planthopper (Sogatella furcifera [Horváth]). An F ₂ population derived from a cross between ADR52 and a susceptible cultivar, Taichung 65 (T65), was used for quantitative trait locus (QTL) analysis. Antibiosis testing showed that multiple loci controlled the high level of BPH resistance in this F ₂ population. Further linkage analysis using backcross populations resulted in the identification of BPH-resistance (antibiosis) gene loci from ADR52. BPH25 co-segregated with marker S00310 on the distal end of the short arm of chromosome 6, and BPH26 co-segregated with marker RM5479 on the long arm of chromosome 12. To characterize the virulence of the most recently migrated BPH strain in Japan, preliminary near-isogenic lines (pre-NILs) and a preliminary pyramided line (pre-PYL) carrying BPH25 and BPH26 were evaluated. Although both pre-NILs were susceptible to the virulent BPH strain, the pre-PYL exhibited a high level of resistance. The pyramiding of resistance genes is therefore likely to be effective for increasing the durability of resistance against the new virulent BPH strain in Japan.

DOI： 10.1007/s00122-011-1723-4

Language：English   Publishing type：Research paper (scientific journal)  

Loss of function of duplicated genes plays an important role in the evolution of postzygotic reproductive isolation. The widespread occurrence of gene duplication followed by rapid loss of function of some of the duplicate gene copies suggests the independent evolution of loss-of-function alleles of duplicate genes in divergent lineages of speciation. Here, we found a novel loss-of-function allele of S27 in the Asian annual wild species Oryza nivara, designated S27-niv^s, that leads to F₁ pollen sterility in a cross between O. sativa and O. nivara. Genetic linkage analysis and complementation analysis demonstrated that S27-niv^s lies at the same locus as the previously identiWed S27 locus and S27-niv^s is a loss-of-function allele of S27. S27-niv^s is composed of two tandem mitochondrial ribosomal protein L27 genes (mtRPL27a and mtRPL27b), both of which are inactive. The coding and promoter regions of S27-niv^s showed a number of nucleotide diVerences from the functional S27-T65⁺ allele. The structure of S27-niv^s is diVerent from that of a previously identiWed null S27 allele, S27-glum^s, in the South American wild rice species O. glumaepatula, in which mtRPL27a and mtRPL27b are absent. These results show that the mechanisms for loss-of-function of S27-niv^s and S27-glum^s are diVerent. Our results provide experimental evidence that diVerent types of loss-of-function alleles are distributed in geographically and phylogenetically isolated species and represent a potential mechanism for postzygotic isolation in divergent species.

DOI： 10.1007/s00122-010-1454-y

Language：English   Publishing type：Research paper (scientific journal)  

To broaden the available rice genetic resources, we developed two populations of introgression lines of cultivated rice (Oryza sativa) carrying donor segments from the wild species Oryza glumaepatula and Oryza meridionalis. These lines contain overlapped introgressed donor segments that covered most parts of the genome of the two donors in the same of O. sativa genetic background (ssp. japonica, cv. Taichung 65). The introgression lines were developed through repeated backcrossing with Taichung 65 as a pollen parent and marker assisted selection. O. glumaepatula introgression lines consist of two sets of the lines (with O. glumaepatula and Taichung 65 cytoplasm, respectively): these comprise a total of 69 lines that cover 79.5 to 89.2% of the Oryza glumaepatula genome. The O. meridionalis introgression lines also consist of two sets of the lines (with O. meridionalis and Taichung 65 cytoplasm, respectively): these comprise a total of 78 lines covering the 81.5 to 98.0% of the Oryza meridionalis genome. These introgression lines significantly broaden rice genetic resources, and will facilitate analyses of the genetics of traits specific to the donor species.

DOI： 10.1270/jsbbs.60.597

Language：English   Publishing type：Research paper (scientific journal)  

The brown planthopper [BPH; Nilaparvata lugens (Stål.)] is one of the most destructive insect pests in Asian rice-growing areas. Two genes conferring resistance to BPH, BPH25(t) and BPH26(t) derived from a BPHresistant indica rice cultivar, Oryza sativa ADR52, have been identified. However, they are linked to genes conferring late heading and hybrid spikelet sterility. To eliminate these unfavorable traits (linkage drag), we generated BC₆F₁ populations carrying BPH25(t) or BPH26(t) in a BPH-susceptible japonica cultivar, Taichung 65, through marker-assisted selection. We selected three near-isogenic lines (NILs) carrying BPH25(t) without late heading date and one NIL carrying BPH26(t) without spikelet sterility from BC₆F₂ progeny that showed between 96.3 and 99.8% of the Taichung 65 genetic background through whole-genome survey. In antibiosis testing, the rates of surviving insects and of females with swollen abdomens were lower on the NILs than on Taichung 65, indicating that bph25(t) and Bph26(t) alleles from ADR52 controlled the resistance to BPH. The NILs will serve as useful resources for (1) monitoring BPH virulence and for (2) increasing resistance to BPH.

DOI： 10.1270/jsbbs.60.639

Language：English   Publishing type：Research paper (scientific journal)  

We have developed two sets of chromosome segment substitution lines (CSSLs) of cultivated rice (Oryza sativa) carrying donor segments from indica cultivars DV85 and ARC10313. The lines in each set contain chromosomal segments that cover most of the donor genome in a uniform genetic background (ssp. Japonica cv. Taichung 65). The starting materials were several recombinant inbred lines derived from the crosses Taichung 65 × DV85 and Taichung 65 × ARC10313. The CSSLs were generated by repeated backcrossing to Taichung 65 (pollen parent), with marker-assisted selection applied at several marker loci. The CSSLs of DV85 (TD-CSSLs) comprise 45 lines that cover 76.6% of the DV85 genome, and the CSSLs of ARC10313 (TA-CSSLs) comprise 44 lines that cover 74.4% of the ARC10313 genome. We investigated the genetic control of days-to-heading in both sets of CSSLs and demonstrated the genetic contribution of several chromosome regions. These CSSLs provide a valuable tool for rice germplasm enhancement, and we expect them to reveal the genetic basis of traits specific to the donor cultivars.

DOI： 10.1270/jsbbs.60.620

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1270/jsbbs.60.459

Language：English   Publishing type：Research paper (scientific journal)  

The green rice leafhopper (GRH), Nephotettix cincticeps Uhler, is a serious insect pest of cultivated rice (Oryza sativa L.) in temperate East Asia. An African rice cultivar, Oryza glaberrima Steud. (IRGC104038), was shown to be highly GRH-resistant at the booting stage. To reveal the genetic basis of the GRH resistance in O. glaberrima, a BC₁F₁ population derived from a cross between a susceptible japonica variety, Taichung 65 (T65), and O. glaberrima was analyzed by quantitative trait locus (QTL) analysis. A single major QTL for GRH resistance, designated qGRH9, was detected on rice chromosome 9, and three minor QTLs were detected on rice chromosomes 3, 7, and 10. A series of O. glaberrima introgression lines (GILs) containing IRGC104038 chromosome segments in the T65 genetic background were evaluated to confirm the genetic effects of the QTLs, and three GILs carrying qGRH9 showed resistance to GRH. Substitution mapping using the GILs revealed that qGRH9 was located between simple sequence repeat (SSR) markers RM215 and RM2482 in a 1.39-Mbp region on the distal region of the long arm of chromosome 9, and tightly linked to RM7306. These SSR markers maybe useful for marker-assisted selection of qGRH9 for improvement of GRH resistance in rice.

DOI： 10.1270/jsbbs.60.336

Language：English   Publishing type：Research paper (scientific journal)  

The green rice leafhopper (GRH), Nephotettix cincticeps Uhler, is a serious insect pest of cultivated rice (Oryza sativa L.) in temperate East Asia. Six GRH-resistance genes (Grh1, Grh2, Grh3, Grh4, Grh5, and Grh6) and one quantitative trait locus (QTL; qGRH4) have been identified. We selected near-isogenic lines (NILs) carrying Grh1, Grh2, Grh4, Grh5, Grh6, and qGRH4 with the japonica genetic background (Taichung 65 cultivar) by means of marker-assisted selection using new simple sequence repeat markers flanking the GRH-resistance genes and QTL. We also developed three pyramided lines (PYLs; Grh2/Grh6-PYL, Grh4/Grh6-PYL, and Grh5/qGRH4-PYL) using each NIL that carried a GRH-resistance gene or QTL. The NILs, PYLs, and donor parents were evaluated by using an antibiosis test. The resistance of Grh1-NIL and Grh5-NIL did not differ significantly from those of the donor parents, whereas the resistances of Grh2-NIL and Grh6-NIL were significantly lower than those of the donor parents. Grh4-NIL and qGRH4-NIL were highly susceptible. The resistance levels of the pyramided lines for Grh2 and Grh6, Grh4 and Grh6, and Grh5 and qGRH4 demonstrated a gene pyramiding effect that significantly increased their resistance. The developed NILs and PYLs should be useful genetic resources for rice improvement and deployment of the resistance genes.

DOI： 10.1270/jsbbs.60.18

Language：English   Publishing type：Research paper (scientific journal)  

The virulence of laboratory strains of the brown planthopper (BPH), Nilaparvata lugens (Stål), and the whitebacked planthopper (WBPH), Sogatella furcifera (Horváth), collected in Japan between 1966 and 2005, was evaluated using rice differential varieties carrying different planthopper resistance genes. The BPH strain collected in 1966 was avirulent to all the rice varieties tested. In contrast, the 1989, 1999 and 2005 strains were virulent to Mudgo, which carries Bph1. The 1999 and 2005 strains were virulent to ASD7 (bph2). Thus, the virulence status of the laboratory BPH strains was the same as in previous reports. The 1989, 1999, and 2005 WBPH strains were virulent to N22 (Wbph1), Mudgo, ASD7, Babawee (bph4) and Chin Saba (bph8); the 1999 and 2005 WBPH strains were also virulent to ARC10239 (Wbph2). Although the virulence status of WBPH in Japan has not previously been studied, the present results suggest that the effectiveness of the Wbph1 resistance gene broke down before 1989, while that of Wbph2 broke down between 1989 and 1999. The present study showed that long-term mass rearing in the laboratory has not affected virulence status. Thus, these strains will be useful to analyze resistance genes against BPH and WBPH.

DOI： 10.1303/aez.2009.149

Language：English   Publishing type：Research paper (scientific journal)  

The demographic parameters of four laboratory strains of the brown planthopper (BPH), Nilaparvata lugens (Stål) collected in Japan between 1966 and 2005, were evaluated using near-isogenic lines (NILs) and pyramided line (PYL) of rice carrying recently identified genes, bph20(t) and Bphz21(t) conferring resistance to BPH. Six traits: adult survivorship, development of female abdomen, nymph survivorship, nymphal developmental period, adult body weight, and oviposition were examined. Based on the adult survivorship and development of female abdomen, the BPH strains of Hatano-66 and Chikugo-89 were avirulent to bph20(t)-NIL and Bph21 (t)-NIL as well as their PYL carrying both bph20(t) and Bph21 (t). On the other hand, the BPH strains of Isahaya-99 and Nishigoshi-05 were virulent to bph20(t)-NIL and Bph21 (t)-NIL but still avirulent to their PYL. Four other demographic parameters of the avirulent strains of BPH showed low nymph survivorship, prolonged nymphal developmental period, light body weight of adults and small number of eggs laid on the resistant lines to BPH. These results suggest that a resistance mechanism such as feeding inhibition caused by the two major genes resistance to BPH, similarly affect both on nymphal and adult stages. The PYL with both bph20(t) and Bph21 (t) had an epistatic effect of resistance to the BPH strains migrated into Japan since 1999.

Language：English   Publishing type：Research paper (scientific journal)  

Completion of the genomic sequencing of rice has enhanced the discovery of new genes. Wild rice relatives are good sources for extending the genetic variation of cultivated rice. Reproductive barriers are commonly found in distant crosses of rice and are attracting attention. The combination of genetic analyses and molecular tools has greatly facilitated the molecular cloning of rice genes based on the classical approach and enabled the tracking of dissemination of the alleles for domestication. Basic information for population genetics study in rice is still being collected and is expected to provide an alternative approach for finding new genes. The wide genetic variation available in wild rice relatives and the combination of various genetic approaches will allow the analysis and understanding of genetic variation at the nucleotide sequence level, as well as the discovery of novel alleles by sequence-based approaches.

DOI： 10.1016/j.pbi.2008.01.008

Language：English   Publishing type：Research paper (scientific journal)  

Deepwater rice (floating rice) can survive under flooded conditions because of their floating ability. We conducted genetic analysis to elucidate the genetic control of floating ability by using an F₂ and BC ₃F₂ populations derived from a cross between deepwater and non-deepwater rice varieties. Internode elongation is the most important trait responsible for this adaptation, and is characterized by two factors: timing of the initiation of elongation and the rate of elongation. The position of the lowest elongated internode (LEI) and the rate of internode elongation (RIE) were used to measure floating ability. Two QTLs for LEI were detected on chromosomes 3 (qLEI3) and 12 (qLEI12). For RIE, two QTLs were detected on chromosomes 1 (qRIE1) and 12 (qRIE12). We confirmed the genetic effects and map positions of qLEI3, qLEI12 and qRIE12 by using BC₃F₂ populations. Characterization of near-isogenic lines of qLEI3, qLEI12 and qRIE12 revealed that the LEI and RIE are at least partly controlled by different genetic pathways. Observation of near-isogenic lines suggested that the introgressed segment of qLEI12 and qRIE12 of chromosome 12 affected the deepwater-responsive elongation.

DOI： 10.1270/jsbbs.58.47

Language：English   Publishing type：Research paper (scientific journal)  

To gain a comprehensive understanding of the genetic regulation of male gametogenesis, we screened and identified mutants for abnormal pollen development in rice (Oryza sativa L.). We gamma-irradiated spikelets of a japonica rice cultivar, Taichung 65, just before and after anthesis. Among 1,000 M₂ lines, 24 lines were identified as mutants for pollen sterility. Progeny tests in M₃ demonstrated that pollen sterility in 12 lines was controlled by single recessive genes, designated sps1-sps12 (sporophytic pollen sterility). In the remaining 12 lines, pollen semi-sterility was under the control of gametophytic genes, designated gps1-gps12 (gametophytic pollen sterility). Linkage analysis revealed that sps6, sps9, and sps12 were mapped on chromosomes 3, 9, and 7, respectively.

DOI： 10.1270/jsbbs.57.331

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The green rice leafhopper (GRH), Nephotettix cincticeps Uhler, is one of the most serious insect pests affecting cultivated rice (Oryza sativa L.) in temperate regions of East Asia. An accession of the wild rice species, Oryza rufipogon Griff. (W1962), was found to be highly resistant to GRH by an antibiosis test. To understand the genetic basis of the GRH resistance, a BC₁F₁ population derived from a cross between a susceptible Japonica variety, Taichung 65 (T65), and a highly resistant accession W1962 was analyzed by quantitative trait loci (QTL) mapping. A single major QTL for GRH resistance was detected on rice chromosome 8. A nearly isogenic population containing segments of the targeted QTL region derived from W1962 was then developed through advanced backcrossing with marker-assisted selection. Further molecular mapping using a BC₄F₂ population revealed that a new resistance gene, designated as Green rice leafhopper resistance 5 (Grh5), was located on the distal region of the long arm of chromosome 8 and tightly linked to the simple sequence repeat markers RM3754 and RM3761. A nearly isogenic line (NIL) carrying Grh5 was subsequently developed in the progeny of the mapping population. The resistance level of Grh5-NIL was compared with those of developed NILs for GRH resistance and was found to have the highest resistance. The DNA markers found to be closely linked to Grh5 would be useful for marker-assisted selection for the improvement of resistance to GRH in rice.

DOI： 10.1007/s00122-006-0270-x

Language：English  

Language：English  

DOI： 10.1111/j.1439-0523.2004.01011.x

Language：English  

Language：English   Publishing type：Research paper (scientific journal)  

The genetic mechanism underlying six palatability properties of cooked rice and three physico-chemical traits was dissected in 66 BC₃F ₂ chromosome segment substitution lines (CSSLs), using a complete linkage map in three successive years. The CSSLs showed transgressive segregation for all traits studied. Significant correlation was detected among most palatability traits. A total of 25 QTLs for the nine traits were identified on nine chromosomes, and many QTLs affecting different quality traits were mapped in the same regions. Six QTLs - qLT-8 for luster, qTD-6 and qTD-8 for tenderness, qIVOE-6 and qIVOE-8 for integrated value of organoleptic evaluation, and qAC-8 for amylose content - were repeatedly detected across the 3 years. Phenotypic values were significantly different between the recurrent parent, cultivar Asominori, and the CSSLs harboring any of the six QTL alleles across the three environments, indicating that these six QTLs were nonenvironment- specific and could be used for marker-assisted selection in rice quality improvement.

DOI： 10.1007/s00122-004-1744-3

Language：English   Publishing type：Research paper (scientific journal)  

Quantitative trait loci (QTL) controlling low temperature germinability (LTG) in rice were identified using 81 recombinant inbreed lines (RILs) derived from a cross between a japonica variety Kinmaze and an indica variety DV85. The accurate condition of LTG evaluation was assumed at 15°C for 10 d after removing the effect of dormancy and the second dormancy. By setting check, the scores of LTG in this study were evaluated. The germination rate at 15°C for 10 d was scored to represent the LTG. The LTG of the RILs ranged from 0 to 99%. By single point analysis, simple interval mapping, and composite interval mapping, 5 putative QTL, qLTG-2, qLTG-6, qLTG-7, qLTG-11 and qLTG-12 were detected on chromosomes 2, 6, 7, 11 and 12. respectively. At the regions of qLTG-2, qLTG-6 and qLTG-11, DV85 alleles increased the LTG, while Kinmaze alleles increased it at the regions of qLTG-7 and qLTG-12. Among the five QTLs reported here, qLTG-2, qLTG-7 and qLTG-12 were newly detected, while the other two QTL-containing regions were close to those previously reported. Epistatic QTL were also detected in this paper.

Language：English   Publishing type：Research paper (scientific journal)  

Nephotettix virescens Distant (green leafhopper: GLH) is one of the major insect pests of rice (Oryza sativa L.) in the temperate rice growing region of Asia. The objective of this study was to determine the chromosome locations of some GLH-resistance genes and conduct genetic analysis of GLH resistance. From a cross between the japonica cultivar Taichung65, which is susceptible to GLH, and indica cultivar ARC10313, which is resistant to GLH, 125 recombinant inbred F₁₀ lines (RIL) were developed. Quantitative trait loci (QTLs) for antibiosis to GLH were detected on chromosomes 3,5,11, and 12. The QTL near XNpb292 on chromosome 12 for GLH mortality was from the japonica cultivar, while the other three QTLs on chromosomes 3, 5, and 11 were from the indica cultivar. The percentages of observed phenotypic variance attributable to the major QTLs on chromosomes 3 and 11 were 25.3% and 56.8%, respectively. These two QTLs were close to two green rice leafhopper (GRH, Nephotettix cincticeps Unler) resistance genes, Grh4 and Grh2, respectively. Using NILs (near isogenic lines) of Grh4 and Grh2, we determined that the interaction of these two GRH resistance genes expressed strong resistance to GLH. Four GLH-resistance QTLs, including two major QTLs linked to XNpb144 on chromosome 3 and G146S on 11, respectively, were identified in this study, and these two major QTLs were located close to Grh2 and Grh4. It may be possible to pyramid these genes to improve resistance to both GRH and GLH.

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2135/cropsci2004.1039a

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

A mapping population of 66 japonica chromosome segment substitution lines (CSSLs) in indica genetic background, derived from a cross between a japonica variety Asominori and an indica variety IR24 by the single-seed descent, backcrossing and marker-assisted selection, was used to detect quantitative trait loci (QTLs) for leaf bronzing index (LBI), stem dry weight (SDW), plant height (PH), root length (RL) and root dry weight (RDW) under Fe²⁺ stress condition in rice. Two parents and 66 japonica CSSLs were phenotyped for the traits by growing them in Fe²⁺ toxicity nutrient solution. A total of fourteen QTLs were detected on chromosome 3,6,7,9,11 and 12, respectively, with LOD of QTLs ranging from 2.72 to 6.63. Three QTLs controlling LBI were located at the region of C515 - XNpb279, R2638 - C1263 and G1465 - C950 on chromosome 3,9 and 11, their contributions to whole variation were 16.45%, 11.16% and 28.02%, respectively. Comparing with the other mapping results, the QTL for LBI located at the region of C515 - XNpb279 on chromosome 3 was identical with the QTL for chlorophyll content on a rice function map. The results indicated that ferrous iron toxicity of rice is characterized by bronzing spots on the lower leaves, which spread over the whole leaves, causing the lower leaves to turn dark gray and to product chlorophyll catabolites or derivatives which reduce cytotoxicity of some heavy metals, such as ferrous iron. Futhermore, the QTL for LBI, SDW and RDW located at the region of G1465 - C950 on chromosome 11 is a major QTL. Whether the QTL for SDW, PH, RL and RDW at the region of XNpb386 - XNpb342 on chromosome 6 is associated with resistance to ferrous iron toxicity need further studies. Our goal is to identify breeding materials for resistance to Fe²⁺ toxicity through marker-assisted selection based on the detected markers.

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1023/A:1026018821472

Language：English   Publishing type：Research paper (scientific journal)  

Ninety-six F₂ lines derived from a cross between a japonica cultivar Taichung 65 and an indica cultivar Bhadua were developed. At the first step, an RFLP linkage map based on the F₂ lines was constructed. The RFLP map contained 94 RFLP makers. F₂ sterility and heading date are important agronomic traits of rice; meanwhile heading date is related to many characters of agronomic importance including sterility. Quantitative trait locus (QTL) analysis was carried out to identify genes controlling F₂ sterility and heading date. Both single factor analysis and interval analysis were applied for QTL analysis. Two QTLs for F₂ spikelet sterility were newly detected on Chromosome 1 and 8. Five QTLs for heading date were detected on Chromosome 1, 4, 6, 8 and 10. Two of them on chromosomel and 10 were newly detected. Near-isogenic lines are now under construction for further QTL analysis and gene mapping of these QTLs newly identified in this paper.

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The brown planthopper (BPH), Nilaparvata lugens Stål, is a serious pest of rice (Oryza sativa L.) in Asia. The rice ovicidal response to BPH is characterized by the formation of watery lesions which result in the death of the eggs. It is one of the factors affecting the suppression of the multiplication of BPH. To detect quantitative trait loci (QTLs) for this ovicidal response, a set of 71 rice recombinant inbred lines (F₁₁) derived from a cross between a Japonica variety Asominori with ovicidal response and an Indica variety IR24 without ovicidal response were phenotyped for grade of watery lesions (GWL) and egg mortality (EM) of BPH. GWL and EM showed a significant positive correlation (P < 0.001) and transgressive segregation was observed for EM. In composite interval mapping for GWL and EM with 293 RFLP marker loci, two QTLs each on the long arm of chromosome 1 (1L) and the short arm of chromosome 6 (6S) were detected for both GWL and EM. The 6S QTL explained 72.1% and 85.1% of the phenotypic variations for GWL and EM, respectively. The QTL on 1L explained 19.8% and 17.8% of the phenotypic variations for GWL and EM, respectively. Both alleles from Asominori increased GWL and EM. The Asominori allele at the 6S QTL was essential for the ovicidal response to BPH and the Asominori allele at the 1L QTL could increase the EM of BPH in the presence of the Asominori allele at the 6S QTL. It is concluded that the two RFLP loci, R1954 linked to 6S QTL and C112 linked to 1L QTL can be used for marker-assisted selection.

DOI： 10.1270/jsbbs.50.291

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The ovicidal response in rice (Oryza sativa L.) to whitebacked planthopper (WBPH), Sogatella furcifera Horvath, is characterized by the formation of watery lesions which result in the death of WBPH eggs. To determine the genetic mechanism of this ovicidal response, a set of 71 rice recombinant inbred (RI) lines (F
₈
, F
₉
, and F
₁₀
) derived from a cross of japonica cultivar Asominori and indica cultivar IR24, the two parents, and the F
₁
were phenotyped for percentage of watery lesions (PWL) and WBPH egg mortality (EM). PWL and EM showed significant positive correlations (P < 0.001) and transgressive segregation was observed for both traits. A total of 10 quantitative trait loci (QTLs) for ovicidal response were detected with 292 RFLP markers in the F
₆
and F
₇
populations by composite interval mapping (LOD ≥ 1.5). Four of 10 QTLs coincided for PWL and EM and each three QTLs were only detected for PWL and EM. The QTL on chromosome 6 (R1954-L688) was most significantly associated with the ovicidal response and accounted for 69.9% of phenotypic variance for PWL (F
₈
) and 46.0% of phenotypic variance for EM (F
₈
). Positive alleles for ovicidal response came from Asominori on chromosomes 1, 3, 6S (short arm), 8, and 12 and from IR24 on chromosomes 2, 6L (long arm), and 10. QTL accumulation from both parents was the genetic basis of the transgressive segregation in the RI population. No epistatic interaction was detected. The Asominori allele on the chromosome 6S QTL was essential to the ovicidal response, and R1954 was found to be a target marker for marker assisted selection.

DOI： 10.2135/cropsci1999.0011183X003900040038x

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Ditelosomic alien addition lines (DtAALs: 2n=2x + 2t) of rice each carrying a pair of telocentric chromosomes of Oryza punctata were isolated at low frequencies (2.5-11.1%) from the progenies of respective monotelosomic alien addition lines (MtAALs: 2n=2x + 1t) 7, 11 and one unidentified MtAAL. During the meiosis, the alien telocentric chromosomes of three DtAALs completely paired at the pachytene and usually separated to each daughter cell at anaphase I, giving rise to viable gametes with an alien telocentric chromosome at high frequencies. These DtAALs were characterized by stable transmission of the alien telocentric chromosome in the progenies. The transmission rates of the alien chromosome were considerably high in the DtAALs, and most plants of their self-pollinated progeny carried at least one alien telocentric chromosome. The pollen and seed fertility were different among three DtAALs. DtAAL 11 carrying a short telocentric chromosome of O. punctata showed high pollen and seed fertility similar to the disomics. The DtAALs showed relatively stable transmission of alien telocentric chromosome(s), where gametes with an extra telocentric chromosome are functional in both female and male germ cells. These suggest that small chromosome fragment with functional centromere, that is a telocentric chromosome, can be transmitted to the progenies and be stable in the next generation. High transmission rates of the alien telocentric chromosome in these DtAALs assure the efficient changes in genetic background of any recipient cultivars by backcrossing.

Language：English   Publishing type：Research paper (scientific journal)  

Three monotelosomic alien addition lines (MtAALs: 2n=2x+1t) and one monoacrosomic alien addition line (MaAAL: 2n=2x+1a) of japonica rice cultivar Nipponbare, each carrying a single chromosome of a diploid strain of O. punctata (W1514) were isolated from the progenies of respective monosomic alien addition lines (MAAL: 2n=2x+1) for chromosomes 2, 4, 7 and 9 of O. punctata. Among them, three were classified as MtAALs carrying extra telocentric chromosomes 2 and 7, and an extra short arm of chromosome 9 in addition to the diploid complement based on the mitotic and meiotic chromosome analysis. The remaining one was similarly classified as a MaAAL carrying an extra acrocentric chromosome consisting of a complete short arm and a heterochromatic proximal region of the long arm of chromosome 4. Three MtAALs were designated as MtAALs 2, 7, and 9S (short arm of chromosome 9), respectively and one MaAAL was designated as MaAAL 4S(4L). Their morphology, seed fertility and the transmission rates of the extra chromosome were compared with those of the respective primary trisomics and MAALs. The plant morphology of MtAAL 2 and MaAAL 48(4L) was similar to that of the respective MAALs, while the plant morphology of MtAAL 9S was similar to that of the disomics. The plant morphology of MtAAL 7 was similar to that of the secondary trisomics for the short arm of chromosome 7. The seed fertility was higher than that of the respective MAALs, suggesting that the addition lines carrying a small chromosome fragment such as telosome or acrosome could give rise to functional gametes. The transmission rates of the extra chromosome were similar to those of the respective MAALs. Most of the PMCs in the MtAALs and the MaAAL showed a 12 II + 1 I (telosome or acrosome) configuration at the diakinesis and first metaphase. These facts suggest that the extra telocentric or acrocentric chromosomes originated from a misdivision of an alien univalent at anaphase I or anaphase II of the respective MAALs and the following chromosome breakage.

DOI： 10.1270/jsbbs1951.48.181

Language：English   Publishing type：Research paper (scientific journal)  

Genomic in situ hybridization (GISH) using total Oryza punctata Kotschy genomic DNA as a probe was applied to detect alien chromosomes transferred from O. punctata (W1514: 2n=2x=24: BB) to O. sativa Japonica cultivar, Nipponbare (2n=2x=24: AA). Only 12 chromosomes in the interspecific hybrids (2n=3x=36: AAB) between autotetraploid of O. sativa cultivar Nipponbare and a diploid strain of O. punctata (W1514) showed intense staining by FITC in mitotic metaphase spreads. Only one homologous pair of chromosomes out of the 12 pairs of O. sativa chromosomes, which is probably chromosome 8, contained similar repetitive sequences as present in O. punctata and were frequently slightly stained by GISH. Monosomic alien addition line(MAAL)s 7 (2n=2x+1=25: AA+7B: Type II) and 10 (2n=2x+1=25: AA+ 10B) were characterized by an additional single chromosome which had been intensely stained by GISH. Thus, GISH using O. punctata total genomic DNA allowed the detection of a specific chromosome transferred into cultivated rice. This method can be useful to search introgressed chromosomal segments or translocated chromosomes in the progenies of the MAALs each carrying an alien chromosome of O. punctata in rice.

Responsible for pages：52 (8):　61-64   Language：Japanese   Book type：General book, introductory book for general audience

Language：Japanese   Book type：Scholarly book

Presentation type：Oral presentation (general)  

Venue：Purdue University   Country：United States  

Molecular cloning of the genes conferring resistance to green rice leafhopper, Nephotettix cincticeps Uhler, in rice, Hideshi Yasui, Plant Breeding Laboratory, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
17th Intl. Plant Resistance to Insects Workshop, West Lafayette, IN, April 9th-12th, 2006

Presentation type：Symposium, workshop panel (public)  

Venue：愛媛大学   Country：Japan  

Genetics of host plant resistance to planthoppers and leafhoppers in rice

Presentation type：Oral presentation (general)  

Venue：水戸， 茨城大学   Country：Japan  

Host plant resistance of nearly-isogenic lines carrying green rice leafhopper resistance gene(s) against the brown planthopper, Nilaparvata lugens Stål. in rice. Yasui, H., D. Fujita and A. Yoshimura (Fac. Agr., Grad. Sch., Kyushu Univ.)

Presentation type：Oral presentation (general)  

Venue：北海道大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：北海道大学   Country：Japan  

Presentation type：Symposium, workshop panel (public)  

Venue：Manila   Country：Philippines  

Other Link： http://www.ricegenetics.com/

Presentation type：Oral presentation (general)  

Venue：Manila   Country：Philippines  

Other Link： http://www.ricegenetics.com/

Presentation type：Symposium, workshop panel (public)  

Venue：Manila   Country：Philippines  

Other Link： http://www.ricegenetics.com/

Presentation type：Symposium, workshop panel (public)  

Venue：Manila   Country：Philippines  

Other Link： http://www.ricegenetics.com/

Presentation type：Oral presentation (general)  

Venue：京都大学   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：対面開催、静岡大学、3月17-18日、2023年3月18日発表   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：対面開催、3月17-18日、2023年3月18日発表   Country：Japan  

Event date： 2022.3

Language：Japanese  

Venue：オンライン開催、3月20-21日、2022年3月20日発表   Country：Japan  

Event date： 2022.3

Language：Japanese  

Venue：日本育種学会141回講演会、オンライン開催、3月20-21日、2022年3月20日発表   Country：Japan  

Event date： 2022.3

Language：Japanese  

Venue：オンライン開催、3月20-21日、2022年3月20日発表   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン開催、2021年9月23日発表   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン開催、2021年9月25日発表、   Country：Japan  

Event date： 2021.9

Language：Japanese  

Venue：オンライン開催、9月23-25日、2021年9月25日発表   Country：Japan  

Event date： 2021.9 - 2021.6

Language：Japanese  

Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：奈良   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：奈良   Country：Japan  

Event date： 2019.3

Language：English   Presentation type：Oral presentation (general)  

Venue：千葉市   Country：Japan  

Event date： 2019.3

Language：English   Presentation type：Oral presentation (general)  

Venue：千葉市   Country：Japan  

【目的】
本研究の目的は，アフリカ産野生イネOryza longistaminataのツマグロヨコバイ（Nephotettix cincticeps Uhler）抵抗性の遺伝的基盤を解明することである. そのために, 野生イネの染色体断片を保有する染色体断片置換系統を育成し，これらの分離集団を利用してツマグロヨコバイ抵抗性のQTL解析を実施した．さらに，検出したQTL領域がヘテロである個体の自殖後代の分離集団を用いて検出したQTLの実証試験を実施した．

【材料および方法】
アフリカ産野生イネOryza longistaminata W1413系統を種子親として，水稲品種日本晴を交雑して得られたF1に日本晴を戻し交雑して染色体部分置換系統を育成した. 供試虫には，1991年に福岡県で採集し，感受性品種上で累代飼育したツマグロヨコバイ個体群を用いた．播種後７日目の幼苗にツマグロヨコバイ一齢幼虫を10頭放飼し, 3, 5, 7日目の昆虫死亡率を算出した．染色体部分置換系統群のうち, 抵抗性個体が分離した系統の後代集団を育成し, 改めて抵抗性検定を実施して候補QTLの実証試験を行った．

【結果】
戻し交雑とSSRマーカー選抜により28系統の染色体部分置換系統群を作出した．28系統の染色体部分置換系統群のうち4系統において抵抗性個体の分離が見られた. これらの分離集団ならびに後代集団のQTL解析の結果, 4つのQTLを検出した (Table 1). それぞれ, 染色体2上の(qGRH2), 染色体 4 上の(qGRH4), 染色体5 上の(qGRH5) 染色体11 (qGRH11) である. いずれもW1413アリルが昆虫死亡率を高める効果を示した. 4つのQTL のうちqGRH11の遺伝効果が最も大きく全体の変異のほぼ20%を説明していた。そのほかの３つのQTLについては全体の変異の12〜20 %を説明していた. それぞれのQTLアリルがW1413ホモ接合である個体のツマグロヨコバイ昆虫死亡率を評価したところ，放飼3日目では近似同質遺伝子系統（NIL）やQTLの集積系統 (PYL) と日本晴との間で差が生じなかったが，放飼5日目以降は顕著な差が見られた. 4つのQTLの集積系統では放飼5日目まではW1413の昆虫死亡率よりも低かったが放飼7日目にはW1413とほぼ同等となった.

【考察】
4つのNILがいずれも抵抗性を示したことから4つのQTLの存在が実証された. 一方で4つのQTLの集積個体が親系統であるW1413とほぼ同等の抵抗性レベルとなったことから, O. longistaminata W1413系統のツマグロヨコバイ抵抗性は4つのQTLによる遺伝的支配を受けておりツマグロヨコバイ抵抗性の遺伝的基盤についてはW1413アリルの集積効果によるものと推察した.

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鳥取市   Country：Japan  

QTLs analysis for resistance to the whitebacked planthopper, Sogatella furcifera, in the rice cultivar ‘ARC10239’ using genotyping-by-sequencing approach.

Event date： 2016.3 - 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋市   Country：Japan  

Exploration of resistance to the green rice leafhopper (Nephotettix cincticeps Uhler) in a core collection of landraces in rice (Oryza sativa L.)

Event date： 2008.12

Venue：開催地：九州大学農学部．   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Kyushu University   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：筑波大学   Country：Japan  

Presentation type：Symposium, workshop panel (public)  

Venue：Manila   Country：Philippines  

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：7

Number of peer-reviewed articles in Japanese journals：0

Proceedings of International Conference Number of peer-reviewed papers：0

Proceedings of domestic conference Number of peer-reviewed papers：0

Type：Competition, symposium, etc. 

Number of participants：450

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：5

Number of peer-reviewed articles in Japanese journals：0

Proceedings of International Conference Number of peer-reviewed papers：0

Proceedings of domestic conference Number of peer-reviewed papers：0

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Number of peer-reviewed articles in Japanese journals：1

Proceedings of International Conference Number of peer-reviewed papers：0

Proceedings of domestic conference Number of peer-reviewed papers：0

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：70

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：400

Type：Competition, symposium, etc. 

Number of participants：400

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：800

Type：Competition, symposium, etc. 

Number of participants：600

Type：Academic society, research group, etc. 

Type：Academic society, research group, etc. 

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop