Laboratory of Plant Cell Biology

TAKAGI, Shingo

Plant Science





Research Theme

When you study functions of biological systems, you may have two types of questions, namely, ‘Why questions’ that ask the reason and significance of their functions, and ‘How questions’ that ask the mechanism responsible for their functions. Basically, ecologists ask ‘Why questions’ while physiologists ask ‘How questions’. However, scientists in both groups have never been always satisfied with their own ways. To develop the frontiers of plant ecology, morphology, and physiology, we are asking ‘How questions’ on the ecological phenomena and ‘Why questions’ on the physiological phenomena.

Ecophysiological studies on photosynthesis

Plants show maximal production of photosynthesis using limited environmental resources, such as light intensity, nitrogen. We are studying about mechanisms of photosynthetic systems on one leaf and whole-plant levels. We also examine effects of growth temperature and virus infection on photosynthesis. Recently, we found that CO2 can be transported via aquaporin on cell membrane in leaves.

Ecophysiological studies on cyanide-resistant respiratory pathway (AOX)

The plant mitochondrial respiratory chain has the cyanide-resistant pathway (AOX), which is uncoupled from ATP production. We examine in vivo activities and regulatory mechanisms of AOX using various techniques. We also study interaction between photosynthesis and respiration.

Cellular responses to environmental fluctuations

Although plants cannot change their locations, they sense and respond to various changes in environmental factors quite precisely. Using cell biological techniques, we are dissecting such processes as chloroplast movement, tropic curvature, and cytoskeletal organizations.

0Chloroplasts face with the intercellular spaces (modified from J. Exp. Biol. 206:1963-1969, 2003). A: Cross section of the adaxial part of a Spinacia oleracea (spinach) leaf. B: Paradermal section of the parenchyma cells of Maesa japonica. Arrowhead in A indicates the stoma and the orange circles in B indicate intercellular spaces. Bars: 25 µm.

1Respiratory chain of plant mitochondria. The alternative oxidase (AOX) is the terminal oxidase and uncoupled from proton transport. In plant mitochondria, uncoupling protein (UCP) can dissipate the proton gradient.


Hayashi T, Harada A, Sakai T, Takagi S Ca2+ transient induced by extracellular changes in osmotic pressure in Arabidopsis leaves: differential involvement of cell wall – plasma membrane adhesion. Plant, Cell and Environment 29 , 661 - 672 (2006)

Yoshida K, Terashima I, Noguchi K Distinct roles of the cytochrome pathway and alternative oxidase in leaf photosynthesis. Plant and Cell Physiology 47 , 22 - 31 (2006)


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