Res. Core for Plant Stress Science

Plant Light Acclimation Research Group

  • We investigate photosynthesis and chloroplast development, the fundamental to photoautotrohic growth of plants. Fluctuation of sun light constantly damages photosynthetic apparatuses located in the chloroplasts, and the excess light energy absorbed by them ultimately leads to growth defect. Our research aims in understanding the acclimation to such light stress, by elucidating photoprotection mechanisms. We also investigate chloroplast differentiation from its precursor proplastid, because it requires the proper assembly and quality control of the photosynthetic apparatuses. Using various experimental methods, we explore these mechanisms at molecular level, which will be useful for modification of photosynthetic activity and genetic engineering.
    Professor:Wataru Sakamoto
    Associate Professor:Ryo Matsushima
    Assistant Professor:Yusuke Kato

Group of Environmental Response Systems

  • Because plants cannot move, they are forced to grow wherever they have germinated. In order to survive, plants evolved a large suite of adaptions to face sudden changes in external environment. It is presumed that sophisticated environmental response mechanisms which control responses to stress exist in plants. In our research group, we aim elucidation of these mechanisms, especially those involved in the recognition and signal transduction of abiotic stress signals in plants. In particular, we investigate the function of plant hormones as important second messengers in plants responding to abiotic stress. We use model plants, molecular genetics, molecular biology, and cell physiology methods to understand various stress sensing mechanisms, and interactions between plant hormones (crosstalk) during stress. In particular, we focus on action of abscisic acid, an important signal that regulates plant adaptation to drought stress by control of stomata opening and transpiration rates in water deficient plants.
    Professor:Takashi Hirayama
    Associate Professor:Izumi Mori
    Assistant Professor:Yoko Ikeda


Group of Plant Stress Physiology

  • Crop production on 70% of the world’s soil is limited by mineral stresses, which include deficiency of essential elements and/or excess of essential and other elements. To improve crop production on these problem soils, our group specifically examines the response of plants to mineral stresses, especially for understanding the tolerance mechanisms from the gene to the whole plant level.
    Professor:Jian Feng Ma
    Associate Professor:Naoki Yamaji
    Assistant Professor:Namiki Mitani
    Assistant Professor:Kengo Yokosho

Group of Plant Growth Regulation

  • Aluminum (Al) ion is one of the major stress factors that limit growth of plants in acidic soils. We aim understanding of both, Al toxicity and Al tolerant mechanisms in plants. Major toxic symptoms in Al-exposure include inhibition of cell elongation and cell death. To understand mechanisms causing Al toxicity, we are now analyzing in detail responses of plant cells to Al at molecular levels, particularly addressing sugar uptake and sugar metabolisms in Al-treated cells. Furthermore, the effects of Al stress in root parts on photosynthesis in shoot parts of plant are analyzed to elucidate how stress occurring in the roots is recognized and compensated at whole plant level. In addition, we previously isolated a wheat Al-tolerant gene (conferring acid-soil-tolerance in plants), ALMT1, which encodes an Al-activated malate transporter. Expression and functional analyses (e.g. activation mechanism by Al) of this gene are currently performed, using molecular-biological and electrophysiological techniques, to complete the functional characterization of ALMT1 gene. Because ALMT gene family is specific to plants, functional diversity of ALMT protein family is investigated. Possible involvement of ALMT genes in response to plant stomatal closure and phosphorus deficiency is under examination.
    Professor:Yoko Yamamoto
    Assistant Professor:Takayuki Sasaki

Group of Molecular and Functional Plant Biology

  • In the Group of Molecular and Functional Plant Biology, we study plant response mechanisms against drought and salt stress environments, especially at the level of molecular function of plant cells and biomembranes. At present, we focus on: (1) Structure and function of water channels (aquaporins); (2) Plant molecular and cell physiological studies of salt and drought stress tolerance mechanism; (3) Functional analysis of membrane transport against stress; (4) Interaction membrane proteins and membranes. As well as general physiological and molecular biological methods, we use a large number of specialized techniques, such as measurement of root functions (water permeability, ion transport)/ Xenopus oocyte expression system/ electrophysiological measurements/ tracer experiments/ complementary transgenic experiments with yeast mutants / bioinformatics.Associate
    Professor:Maki Katsuhara
    Assistant Professor:Mineo Shibasaka

Group of Plant-Microbe Interactions

  • Plant growth is influenced by a large variety of microorganisms including beneficial and harmful ones. Among them, plant-infecting viruses severely damage crops, while mycoviruses-infected phytopathogenic fungi serve as biocontrol (virocontrol) agents. In addition, an increasing number of plant-mutualistic bacteria and fungi that enhance plant growth and promote stress tolerance in plants have been found. In the Group of Plant-Microbe Interactions, we study complex, dynamic interactions between plants and microorganisms to develop novel methods and approaches for plant protection against biotic and abiotic stress factors.
    Professor:Nobuhiro Suzuki
    Associate Professor:Hideki Kondo
    Associate Professor:Akio Tani
    Assistant Professor:Kiwamu Hyodo

Group of Plant-Insect Interactions

  • Plant defenses against insects evolved in a long-term process of co-evolution of plants and herbivorous insects. In this process, plants developed enormous diversity in their chemical and mechanical defenses. Various defense strategies of plants against insects that involve direct and indirect defense mechanisms are studied in the group. Insecticides are principal control measures in integrated pest management (IPM) but insecticide sprays also damage natural enemies of arthropod pests. In the group, we target eco-friendly plant protection based on the use of selective insecticides that may facilitate the integration of natural enemies in IPM.
    Professor:Ivan Galis
    Assistant Professor:Tomonori Shinya