||Eiji Gotoh, Noriyuki Suetsugu, Wataru Yamori, Kazuhiro Ishishita, Ryota Kiyabu, Masako Fukuda, Takeshi Higa, Bungo Shirouchi, Masamitsu Wada, Chloroplast Accumulation Response Enhances Leaf Photosynthesis and Plant Biomass Production, Plant Physiology, 10.1104/pp.18.00484, 178, 3, 1358-1369, 2018.11, Under high light intensity, chloroplasts avoid absorbing excess light by moving to anticlinal cell walls (avoidance response), but under low light intensity, chloroplasts accumulate along periclinal cell walls (accumulation response). In most plant species, these responses are induced by blue light and are mediated by the blue light photoreceptor, phototropin, which also regulates phototropism, leaf flattening, and stomatal opening. These phototropin-mediated responses could enhance photosynthesis and biomass production. Here, using various Arabidopsis (Arabidopsis thaliana) mutants deficient in chloroplast movement, we demonstrated that the accumulation response enhances leaf photosynthesis and plant biomass production. Conspicuously, phototropin2 mutant plants specifically defective in the avoidance response but not in other phototropin-mediated responses displayed a constitutive accumulation response irrespective of light intensities, enhanced leaf photosynthesis, and increased plant biomass production. Therefore, our findings provide clear experimental evidence of the importance of the chloroplast accumulation response in leaf photosynthesis and biomass production..
||Eiji Gotoh, Kohei Oiwamoto, Shin Ichiro Inoue, Ken Ichiro Shimazaki, Michio Doi, Stomatal response to blue light in crassulacean acid metabolism plants Kalanchoe pinnata and Kalanchoe daigremontiana, Journal of Experimental Botany, 10.1093/jxb/ery450, 70, 4, 1367-1374, 2019.02, Blue light (BL) is a fundamental cue for stomatal opening in both C 3 and C 4 plants. However, it is unknown whether crassulacean acid metabolism (CAM) plants open their stomata in response to BL. We investigated stomatal BL responses in the obligate CAM plants Kalanchoe pinnata and Kalanchoe daigremontiana that characteristically open their stomata at night and close them for part of the day, as contrasted with C 3 and C 4 plants. Stomata opened in response to weak BL superimposed on background red light in both intact leaves and detached epidermal peels of K. pinnata and K. daigremontiana. BL-dependent stomatal opening was completely inhibited by tautomycin and vanadate, which repress type 1 protein phosphatase and plasma membrane H + -ATPase, respectively. The plasma membrane H + -ATPase activator fusicoccin induced stomatal opening in the dark. Both BL and fusicoccin induced phosphorylation of the guard cell plasma membrane H + -ATPase in K. pinnata. These results indicate that BL-dependent stomatal opening occurs in the obligate CAM plants K. pinnata and K. daigremontiana independently of photosynthetic CO 2 assimilation mode..
||Gotoh Eiji, Suetsugu Noriyuki, Higa Takeshi, Matsushita Tomonao, Tsukaya Hirokazu, Wada Masamitsu, Palisade cell shape affects the light-induced chloroplast movements and leaf photosynthesis, SCIENTIFIC REPORTS, 10.1038/s41598-018-19896-9, 8, 2018.01, Leaf photosynthesis is regulated by multiple factors that help the plant to adapt to fluctuating light conditions. Leaves of sun-light-grown plants are thicker and contain more columnar palisade cells than those of shade-grown plants. Light-induced chloroplast movements are also essential for efficient leaf photosynthesis and facilitate efficient light utilization in leaf cells. Previous studies have demonstrated that leaves of most of the sun-grown plants exhibited no or very weak chloroplast movements and could accomplish efficient photosynthesis under strong light. To examine the relationship between palisade cell shape, chloroplast movement and distribution, and leaf photosynthesis, we used an Arabidopsis thaliana mutant, angustifolia (an), which has thick leaves that contain columnar palisade cells similar to those in the sun-grown plants. In the highly columnar cells of an mutant leaves, chloroplast movements were restricted. Nevertheless, under white light condition (at 120 µmol m−2 s−1), the an mutant plants showed higher chlorophyll content per unit leaf area and, thus, higher light absorption by the leaves than the wild type, which resulted in enhanced photosynthesis per unit leaf area. Our findings indicate that coordinated regulation of leaf cell shape and chloroplast movement according to the light conditions is pivotal for efficient leaf photosynthesis..
||Noriyuki Suetsugu*, Takeshi Higa*, Eiji Gotoh*, Masamitsu, Light-Induced Movements of Chloroplasts and Nuclei Are Regulated in Both Cp-Actin-Filament-Dependent and -Independent Manners in Arabidopsis thaliana, PLOS ONE, 10.1371/journal.pone.0157429, 11, 6, *These authors contributed equally., 2016.06.
||Ishishita Kazuhiro, Noriyuki Suetsugu, Yuki Hirose, Tomonao Matsushita, Takeshi Higa, Masamitsu Wada, Michio Doi, Eiji Gotoh, Functional characterization of blue-light-induced responses and PHOTOTROPIN 1 gene in Welwitschia mirabilis, JOURNAL OF PLANT RESEARCH, 10.1007/s10265-016-0790-7, 129, 2, 175-187, 2016.03.