CDKG1 Is Required for Meiotic and Somatic Recombination Intermediate Processing in Arabidopsis

Abstract

Short title: The role of CDKG1 in recombinationOne-sentence summary: The cyclin-dependent kinase CDKG1 stabilises recombination intermediates during male meiosis and DNA damage-induced somatic homologous recombination. ABSTRACTThe Arabidopsis thaliana cyclin-dependent kinase G1 (CDKG1) is necessary for recombination and synapsis during male meiosis at high ambient temperature. In the cdkg1-1 mutant, synapsis is impaired and there is a dramatic reduction in the number of class I crossovers resulting in univalents at metaphase I and pollen sterility. Here we demonstrate that CDKG1 is necessary for the processing of recombination intermediates in the canonical ZMM recombination pathway and that loss of CDKG1 results in increased class II crossovers. While synapsis and events associated with class I crossovers are severely compromised in a cdkg1-1 mutant, they can be restored by increasing the number of recombination intermediates in the double cdkg1-1 fancm-1 mutant. Despite this, recombination intermediates are not correctly resolved, leading to the formation of chromosome aggregates at metaphase I. Our results show that CDKG1 acts early in the recombination process and is necessary to stabilize recombination intermediates. Finally, we show that the effect on recombination is not restricted to meiosis and that CDKG1 is also required for normal levels of DNA damage-induced homologous recombination in somatic tissues. . Both ATM and ATR promote the efficient and accurate processing of programmed meiotic double-strand breaks. The Plant Journal 55, 629-638. Dangel, N.J., Knoll, A., and Puchta, H. (2014). MHF1 plays Fanconi anaemia complementation group M protein (FANCM)-dependent and FANCM-independent roles in DNA repair and homologous recombination in plants.

A Functional Kinase Is Necessary for Cyclin-Dependent Kinase G1 (CDKG1) to Maintain Fertility at High Ambient Temperature in Arabidopsis

“…CDKG1 proteins where the Aspartic acid at position 426 within the ATP pocket was mutated were unable to rescue the cdkg1-1 fertility defect, indicating that the functions of CDKG1 during meiosis and pollen formation are dependent on its kinase activity. During male meiosis, CDKG1 is necessary to stabilize early recombination intermediates that are needed to maintain synapsis and normal levels of Class I crossovers (Nibau et al, 2020b). Based on the data obtained using versions with a mutated ATP binding pocket, we speculate that CDKG1 is doing this by phosphorylating meiotic proteins involved in early meiotic recombination.…”

“…In contrast, plants lacking CDKG2 are fully fertile at both high and low temperatures (Zheng et al, 2014). Our recent work has shown that, at high ambient temperature, CDKG1 is required for meiotic chromosome pairing and recombination by helping to stabilize recombination intermediates (Zheng et al, 2014;Nibau et al, 2020b). At low temperature, chromosome pairing and recombination are not affected by the absence of CDKG1 (Zheng et al, 2014;Nibau et al, 2020b).…”

Double Crossed: CDKG1 Regulates Crossover Formation by Stabilizing Meiotic and Somatic Recombination Intermediates

“…Taken together, Nibau et al (2020) have established that CDKG1 is necessary for the stabilization of recombination intermediates during both male meiosis and somatic homologous recombination following DNA damage. The loss of CDKG1 results in impaired synapsis and fewer class I COs.…”

“…In this issue, Nibau et al (2020) determined the precise effect of CDKG1 on recombination and synapsis by comparing the cdkg1-1 mutant with other Arabidopsis mutants possessing wellcharacterized defects at different stages of crossover formation and junction resolution. They first crossed the cdkg1-1 mutant with the msh5-2 mutant, which contains a T-DNA insertion in AtMSH5, a ZMM protein implicated in the class I CO pathway.…”

“…Unpaired regions are indicated by the presence of ASY1 (red) and paired regions by the presence of ZYP1 (gray). (Adapted from Nibau et al [2020], Figure 4.) [OPEN] Articles can be viewed without a subscription.…”