Functional Exploration Of Apparent Genetic Factors CLF, LHP1 And SDG2 In Arabidopsis Thaliana In Homologous Recombination

Homologous recombination (HR) is an important pathway during life processes both for chromosome pairing and exchange during meiosis and for repairing DNA damages in somatic cells. PcG protein CLF and TrxG protein SDG2, which catalyze methylation of histone H3K27 and H3K4 respectively, are founded to play important roles during plant growth and development. Abnormal meiosis usually influence the fertility. Given the poor fertility of clf-29 and 1hp1/tfl2 mutants, we used two visual assays to investigate the crossover (CO) frequency of meiotic HR in these mutants background comparing with the wild type plants. Although the meiotic HR frequencies in the mutant clf-29 or 1hp1/tf12 is not significantly different from that in wild type, somatic HR is impaired in clf-29 under both standard growth conditions and bleomycin-treated growth conditions. Besides, we found sdg2 mutant was also included in somatic HR assay, showing elevated level of somatic recombination. Furthermore, analysis of DNA damages and the expression levels of DNA repair genes also implied the negative correlation between CLF and SDG2,indicating an antagonistic role of H3K27 and H3K4 methylation in somatic HR regulation. Thus our results demonstrate that CLF and SDG2, which have been reported to be important for the transcription regulation, are required for proper somatic recombination in Arabidopsis in an antagonistic way.