Arabidopsis FLC and MAF1 interact with HDA9 involved in flowering time control

FLC is a key regulator of flowering in Arabidopsis thaliana. FLC inhibits flowering by repressing FT and SOC1 genes that promote flowering. There are five FLC clade members, MAF1, MAF2, MAF3, MAF4 and MAF5 in Arabidopsis. Like FLC, MAF1 to MAF5 also act as repressors of flowering. Arabidopsis HDA9 belongs to the RPD3/HDA1 histone deacetylase, and hda9 mutants have an early flowering phenotype. In this study, we analyzed the flowering phenotype of flc, maf1 and hda9 mutants. Compared with wild type plants, flc, maf1 and hda9 plants flowered earlier under both long-day or short-day conditions. In addition, the expression of FT and SOC1 was significantly increased in maf1 and hda9 plants. Further analysis indicated that HDA9 interacted with FLC and MAF1 in bimolecular fluorescence complementation and yeast two- hybrid assays. These results indicated that HDA9 may interact with FLC and MAF1 to repress the expression of FT and SOC1.