Division of Plant Sciences

Functional Plant Research Unit

Analyses of carbon and nitrogen metabolisms involved in biomass production and mechanisms of responses to environmental signals of plants

  Plants assimilate inorganic carbon through photosynthesis and inorganic nitrogen absorbed from roots to produce organic compounds we use as food and energy resources. Plants are also capable of acclimating to fluctuating environments so as to optimize their own biological functions. We investigate molecular mechanisms of these fundamental processes of plants, aiming at improving their productivity and environmental adaptability. The food and energy production by plants depends on assimilation of carbon and nitrogen, and production is repressed if either process is limited. Assimilation and subsequent metabolism of carbon and nitrogen are not independent but they interact with one another in response to carbon/nitrogen supply and product demand. We are investigating mechanisms of metabolic interactions, translocation of metabolites, and starch accumulation in grains. The growth of plants is governed by their own developmental program, which is highly influenced by a variety of environmental factors, such as temperature, the quality and intensity of light, and the day length. Although environmental conditions vary every hour, day or season, plants have mechanisms to recognize and acclimate to surrounding environments. We are investigating mechanisms of plant development and how plants recognize and respond to environments.

Assimilation of inorganic carbon (photosynthesis) and inorganic nitrogen supports production of food and energy by plants

Starch in amyloplasts of the rice grain

Images observed with a confocal microscope (left) and scanning electron microscope (right) are shown.

Ectopic development of chloroplasts

Overexpression of a key factor for the chloroplast development makes green chloroplasts accumulate in vascular bundles which normally have a few chloroplasts (arrowhead) in rice.

  • Plants have an internal biological clock to track the time of day and recognize the day length from light environments. Flowering of rice, a shortday plant, is induced when days grow shorter than the threshold length.