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Cyclin‐dependent kinase‐activating kinases CDKD ;1 and CDKD ;3 are essential for preserving mitotic activity in Arabidopsis thaliana
Author(s) -
Takatsuka Hirotomo,
UmedaHara Chikage,
Umeda Masaaki
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12872
Subject(s) - kinase , arabidopsis thaliana , microbiology and biotechnology , mitosis , chemistry , arabidopsis , cyclin dependent kinase , cyclin , biology , biochemistry , cell cycle , cell , gene , mutant
Summary For the full activation of cyclin‐dependent kinases ( CDK s), not only cyclin binding but also CDK phosphorylation is required. This activating phosphorylation is mediated by CDK ‐activating kinases ( CAK s). Arabidopsis has four genes showing similarity to vertebrate‐type CAK s, three CDKD s ( CDKD ;1 ‐ CDKD ;3 ) and one CDKF ( CDKF ;1 ). We previously found that the cdkf;1 mutant is defective in post‐embryonic development, even though the kinase activities of core CDK s remain unchanged relative to the wild type. This raised a question about the involvement of CDKD s in CDK activation in planta . Here we report that the cdkd;1 cdkd;3 double mutant showed gametophytic lethality. Most cdkd;1‐1 cdkd;3‐1 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 CDKD ;1 and CDKD ;3 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, CDKF ;1 expression in the cdkd;1‐1 cdkd;3‐1 mutant could not rescue the gametophytic lethality. These results suggest that, in Arabidopsis, CDKD ;1 and CDKD ;3 function as CAK s 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 CDK s, CDKA , CDKB 1 and CDKB 2, thereby governing cell cycle progression throughout plant development.