Arabidopsis RPD3-type histone deacetylases form multiple plant-specific complexes that are required for preventing overexpression of stress-induced genes (RNA-Seq)

Although the Arabidopsis thaliana RPD3-type histone deacetylases have been known to form SIN3 histone deacetylase complexes that are conserved in eukaryotes, it is unknown whether they also form other types of histone deacetylase complexes. Here, we performed affinity purification followed by mass spectrometry and demonstrated that the Arabidopsis RPD3-type histone deacetylases HDA6 and HDA19 can interact with several previously uncharacterized proteins and form three types of plant-specific histone deacetylase complexes, which we named SANT, ESANT, and ARID. RNA-seq indicated that HDA6 and HDA19 function together with other components of the histone deacetylase complexes and co-regulate the expression of a number of genes. HDA6 and HDA19 have been thought to repress gene transcription by histone deacetylation. We found that the histone deacetylase complexes can also repress gene expression via certain histone-deacetylation-independent mechanisms. In the mutants of the histone deacetylase complexes, the expression of a number of stress-induced genes was up-regulated. Several mutants of the histone deacetylase complexes showed severe retardation in growth. Considering that the growth retardation is thought to be a trade-off for the increase of stress tolerance, we predict that the histone deacetylase complexes identified in this study prevent overexpression of stress-induced genes and thereby ensure normal growth of plants under non-stress conditions. Overall design: Examination of the mRNA expression of wild type and seven mutants grown under long day conditions.