The Cdk1/Cdk2 homolog CDKA;1 controls the recombination landscape in Arabidopsis

Significance Cyclin-dependent kinases are the main drivers of the mitotic cell cycle. Here, we show that the activity of the main cell-cycle regulator in the model plant Arabidopsis, CDKA;1, also governs one of the most important processes in meiosis: the formation of meiotic cross-overs. We show that CDKA;1 activity especially affects the major class of meiotic cross-overs, known as class I cross-overs. We find that lowering kinase activity leads to a progressive loss of cross-overs, of which cross-overs near the chromosome ends are the last to disappear. Conversely, an increase of kinase activity increases the rate of cross-over formation.
Little is known how patterns of cross-over (CO) numbers and distribution during meiosis are established. Here, we reveal that cyclin-dependent kinase A;1 (CDKA;1), the homolog of human Cdk1 and Cdk2, is a major regulator of meiotic recombination in Arabidopsis. Arabidopsis plants with reduced CDKA;1 activity experienced a decrease of class I COs, especially lowering recombination rates in centromere-proximal regions. Interestingly, this reduction of type I CO did not affect CO assurance, a mechanism by which each chromosome receives at least one CO, resulting in all chromosomes exhibiting similar genetic lengths in weak loss-of-function cdka;1 mutants. Conversely, an increase of CDKA;1 activity resulted in elevated recombination frequencies. Thus, modulation of CDKA;1 kinase activity affects the number and placement of COs along the chromosome axis in a dose-dependent manner.