HDA19Interacts With HSL1and Participates In The Repression Of Seed Maturation Genes In Arabidopsis Seedlings

The seed maturation genes are specifically and highly expressed during lateembryogenesis. We found that HISTONE DEACETYLASE19(HDA19) wasinvolved in the repression of the seed maturation gene expression in seedlings.Elevated transcription of seed maturation genes was found in the hda19mutantseedlings, which was accompanied by the enrichment of gene activation marks suchas H3ac, H4ac, H3K9ac, H3K14ac, H4K5ac, H4K12ac as well as H3K4me3in thepromoter and/or coding regions. In contrast, decreased levels of gene repressionmarks, H3K9me2, H3K27me3, and H4K20me2, were also observed. Yeast two-hybrid,bimolecular fluorescence complementation and coimmunoprecipitation assaysrevealed that HDA19interacted with the HIGH-LEVEL EXPRESSION OFSUGAR-INDUCIBLE GENE2-LIKE1(HSL1), and the zinc-finger CW domain ofHSL1was responsible for the interaction between HDA19and HSL1. Furthermore,elevated transcription of certain seed maturation genes was also found in the hsl1mutant seedlings, which was also accompanied by the enrichment of gene activationmarks H3ac, H4ac, and H3K4me3and decreased level of gene repression markH3K27me3. Chromatin immunoprecipitation assays showed that HDA19coulddirectly bind to the chromatin of certain seed maturation genes. These results suggestthat HDA19and HSL1may act synergistically to repress seed maturation geneexpression during germination. In addition, hsl1hda19double mutants were generated and genetic analysis revealed that the homozygous hsl1hda19doublemutants were embryonic lethal, suggesting that HDA19and HSL1may together playa vital role during embryogenesis.