title: Control of in vitro organogenesis by cyclin-dependent kinase activities in plants.
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.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kato
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yoshida
authors.forename: Saburo
authors.initials: S
authors.lastname: Yamamura
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uchimiya
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
mesh_terms: D002454:Cell Differentiation; D002455:Cell Division; D018844:Cyclin-Dependent Kinases / Q000502:physiology*; D003583:Cytokinins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008954:Models, Biological; D012275:Oryza / Q000235:genetics* / Q000502:physiology*; D010641:Phenotype; D018515:Plant Leaves / Q000378:metabolism; D018521:Plant Physiological Phenomena; D030821:Plants, Genetically Modified; D011687:Purines / Q000494:pharmacology; D000077546:Roscovitine; D013997:Time Factors; D014026:Nicotiana / Q000235:genetics
chemical_list: D003583:Cytokinins; D004791:Enzyme Inhibitors; D011687:Purines; D000077546:Roscovitine; D018844:Cyclin-Dependent Kinases