Functional divergence of CDK-activating kinases during embryogenesis

Abstract

Cyclin-dependent kinases (CDKs) regulate cell cycle progression, being activated by phosphorylation of the conserved threonine residue within T-loop. This phosphorylation is catalyzed by CDK-activating kinase (CAK). Arabidopsis has four genes encoding CAKs, namely CDKD;1, CDKD;2, CDKD;3 and CDKF;1. We previously reported that the cdkf;1 mutants showed severe defects in post-embryonic development but not in embryonic development, while the cdkd;1 cdkd;3 double mutants were embryonic-lethal. These results suggest diverged functions of CAKs during plant development. However, the spatio-temporal expression patterns of CAKs, which may cause differential roles in developmental processes, remain unknown. Hence, we are conducting detailed expression analyses of CAKs, especially during embryogenesis. We shall discuss why the CAK functions are so diverged in terms of expression patterns during embryogenesis.