Cyclin‐dependent kinase‐activating kinases CDKD;1 and CDKD;3 are essential for preserving mitotic activity in Arabidopsis thaliana. (25th May 2015)

• Record Type: Journal Article
• Authors: Takatsuka, Hirotomo; Umeda‐Hara, Chikage; Umeda, Masaaki
• Is Part Of: Plant journal. Volume 82:Number 6(2015:Jun.)
• Page Start: 1004
• Page End: 1017
• Publication Date: 2015-05-25
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12872
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12872-abs-0001"> <title>Summary</title> <p>For the full activation of cyclin‐dependent kinases (CDKs), not only cyclin binding but also CDK phosphorylation is required. This activating phosphorylation is mediated by CDK‐activating kinases (CAKs). Arabidopsis has four genes showing similarity to vertebrate‐type CAKs, three <italic>CDKD</italic>s (<italic>CDKD;1</italic>‐<italic>CDKD;3</italic>) and one <italic>CDKF</italic> (<italic>CDKF;1</italic>). We previously found that the <italic>cdkf;1</italic> mutant is defective in post‐embryonic development, even though the kinase activities of core CDKs remain unchanged relative to the wild type. This raised a question about the involvement of CDKDs in CDK activation <italic>in planta</italic>. Here we report that the <italic>cdkd;1 cdkd;3</italic> double mutant showed gametophytic lethality. Most <italic>cdkd;1‐1 cdkd;3‐1</italic> pollen grains were defective in pollen mitosis I and II, producing one‐cell or two‐cell pollen grains that lacked fertilization ability. We also found that the double knock‐out of <italic>CDKD;1</italic> and <italic>CDKD;3</italic> caused arrest and/or delay in the progression of female gametogenesis at multiple steps. Our genetic analyses revealed that the functions of CDKF;1 and CDKD;1 or CDKD;3 do not overlap, either during gametophyte and embryo development or in post‐embryonic development. Consistent with these analyses, <italic>CDKF;1</italic> expression in the <italic>cdkd;1‐1 cdkd;3‐1</italic> mutant could not rescue the gametophytic lethality. These results suggest that, in Arabidopsis, CDKD;1 and CDKD;3 function as CAKs controlling mitosis, whereas CDKF;1 plays a distinct role, mainly in post‐embryonic development. We propose that CDKD;1 and CDKD;3 phosphorylate and activate all core CDKs, CDKA, CDKB1 and CDKB2, thereby governing cell cycle progression throughout plant development.</p> </abstract>