|Budget Amount *help
¥106,210,000 (Direct Cost : ¥81,700,000、Indirect Cost : ¥24,510,000)
Fiscal Year 2007 : ¥22,100,000 (Direct Cost : ¥17,000,000、Indirect Cost : ¥5,100,000)
Fiscal Year 2006 : ¥22,100,000 (Direct Cost : ¥17,000,000、Indirect Cost : ¥5,100,000)
Fiscal Year 2005 : ¥22,100,000 (Direct Cost : ¥17,000,000、Indirect Cost : ¥5,100,000)
Fiscal Year 2004 : ¥16,640,000 (Direct Cost : ¥12,800,000、Indirect Cost : ¥3,840,000)
Fiscal Year 2003 : ¥23,270,000 (Direct Cost : ¥17,900,000、Indirect Cost : ¥5,370,000)
The aim of this study is to understand how inter-cellular signaling molecules regulate plant development. This study focused on biosynthesis, perception, signal transduction, and biological role of a classical plant hormone, cytokinin; and identification of new signaling molecules. Before the start of this project, we identified biosynthetic enzymes and a receptor of cytokinins, however, detailed analysis was yet to be done. In this project, we have clarified the biosynthetic routes of cytokinins, using multiple mutants of cytokinin biosynthetic isopentenyltransferases and tRNA modifying isopentenyltransferases. The multiple mutant also revealed the functions of endogenous cytokinins, including a novel function, regulation of cambial activity. We also disrupted all cytokinin receptor genes, which provided evidence that cytokinins are perceived exclusively by CRE1-class histidine kinases. We explored into detailed mechanisms of cytokinin signal transduction, showing that cytokinins regulate bidirectional phosphorelay signaling. We also screened for novel intercellular signaling molecules. For the first screening we overexpressed genes coding for putative secretory small products, and we found a number of genes that cause interesting phenotypes. Among those genes, we examined the roles of two genes, for which we named EPF1 and EPF2. EPF1 regulates the pattern of stomata, and EPF2 regulates epidermal cell density. Although the action-timings of EPF1 and EPF2 differ, they are perceived and transduced by the same set of proteins, TMM receptor-like protein, ER-family receptor kinases, and a MAPKKK, YODA. We will clarify the function of other candidate signaling-molecules.