Histone deacetylase HDA19 interacts with histone methyltransferase SUVH5 to regulate seed dormancy in Arabidopsis

Seed dormancy controls the timing of germination and plays a significant role in adaptation and evolution of seed plants. In this study, a yeast two-hybrid, pull-down assay and co-immunoprecipitation assay were used to ascertain the protein relationship of SUVH5 and HDA19. Both qRT-PCR and ChIP-qPCR were used to examine the molecular mechanism of how HDA19 and SUVH5 regulate seed dormancy. The results demonstrated that histone methyltransferase SUVH5 interacted with histone deacetylase HDA19 in vivo and in vitro. In addition, they showed that mutants of HDA19 could deepen seed dormancy, and that SUVH5 had the same effect. The hda19 suvh5 double mutant displayed a higher level of seed dormancy than the single mutants hda19 or suvh5. Moreover, the expression of seed dormancy-related genes increased in hda19, suvh5 and in hda19 suvh5 double mutant plants, which was associated with increased histone H3 acetylation (H3ac), but decreased histone H3 Lys 9 dimethylation (H3K9me2). ChIP assays proved that HDA19 could directly integrate into the chromatin of genes regulating seed dormancy. Taken together, our results show that HDA19 and SUVH5 work together and have a negative role in seed dormancy.