Combinatorial regulation of CLF and SDG8 during Arabidopsis shoot branching

Abstract

SET domain group 8 (SDG8) serves as multifunctional H3 methyltransferase to be involved in various processes in plants. To better understand its functions, an EMS mutagenesis of sdg8-2 seeds was performed for the enhancers of sdg8-2, and an allele of CURLY LEAF (clf100) was identified in the study, which enhanced the phenotype of sdg8-2, such as early flower, abortion, and more shoot branches. Real-time PCR analysis indicated that the simultaneous disruption of SDG8 and CLF can lead to synergistic or antagonistic effect on transcriptional accumulation of shoot branching regulatory genes. Among the 16 genes examined in the study, the transcriptional accumulation of LATERAL SUPPRESSOR (LAS) and UDP-GLYCOSYLTRANSFERASE 74E2 (UGT74E2) displayed most significant enhancement in double mutant. Furthermore, the chromatin immunoprecipitation assay indicated that the excess expressions of LAS and UGT74E2 in double mutant were associated with the state of H3K trimethylation marks at their locus, showing the reduction of H3K27me3 level, as well as an elevated enrichment of H3K36me3 at LAS locus and H3K4me3 at UGT74E2 locus. These results indicated that CLF and SDG8 can play a combinatorial role in regulation of shoot branching via maintaining proper histone markers for appropriate gene expression.