GENETIC ANALYSIS OF POLYCOMB GROUP GENE-MEDIATED FLOWERING CONTROL IN ARABIDOPSIS

Abstract

In Arabidopsis life cycle, flowering is pivotal to reproductive success. Polycomb group (PcG) genes are well known to control gene expressions, including key flowering-regulatory gene FLOWERING LOCUS C. In Arabidopsis, Polycomb repressive complex 2 (PRC2) deposits histone H3 lysine-27 trimethylation (H3K27me3) in target genes to repress their expression. Recent studies have shown that CURLY LEAF (CLF) functions in the PRC2 complex to deposit H3K27 trimethylation on FLC chromatin, leading to FLC repression in rapid-cycling Arabidopsis. My project aims to understand how FLC expression is regulated by CLF. To this end, I have screened two mutagenized Arabidopsis populations using a clf mutant, and identified nine mutants in which CLF-mediated FLC repression appeared to be impaired. Further molecular and genetic analyses revealed that these nine mutations are required for FLC silencing by CLF. The findings from this study suggest that PcG-mediated flowering control is complicated and involves various players in Arabidopsis.