Control of in vitro organogenesis by cyclin-dependent kinase activities in plants
- Masatoshi Yamaguchi*,
- Hisashi Kato†,
- Shigeo Yoshida†,
- Saburo Yamamura‡,
- Hirofumi Uchimiya*, and
- Masaaki Umeda*,§
- *Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan; †RIKEN Plant Science Center, Functional Control Research Group, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan; and ‡Iwate Biotechnology Center, Narita 22-174-4, Kitakami-shi, Iwate 024-0003, Japan
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Communicated by Takayoshi Higuchi, Kyoto University, Kyoto, Japan, May 2, 2003 (received for review March 25, 2003)
Abstract
Little is known concerning the mechanisms by which auxin and cytokinin exert their effects on proliferation and differentiation. Cyclin-dependent kinases (CDKs) are major regulators of the eukaryotic cell cycle, thus they are assumed to control cell differentiation as well as proliferation in response to phytohormone signals. Here, we overexpressed rice R2 cDNA, which encodes a CDK-activating kinase, in tobacco leaf explants by using the glucocorticoid-mediated transcriptional induction system. Transient expression of R2 during the first 7 days of culture triggered callus formation in the absence of cytokinin. This phenotype was enhanced by higher expression of R2 or coexpression of cyclin H, and suppressed by treatment with roscovitine, a CDK inhibitor. R2 expression at a later stage did not prevent cells from differentiation into roots, suggesting a restricted period for sensing CDK activities that control differentiation fate of cells during organogenesis.
Footnotes
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↵ § To whom correspondence should be addressed. E-mail: mumeda{at}iam.u-tokyo.ac.jp.
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Abbreviations: CDK, cyclin-dependent serine/threonine protein kinase; CAK, CDK-activating kinase; DEX, dexamethasone; NAA, naphthaleneacetic acid.
- Copyright © 2003, The National Academy of Sciences
