Frontiers in Plant Science (Oct 2019)
Transcriptome Analysis of the Hierarchical Response of Histone Deacetylase Proteins That Respond in an Antagonistic Manner to Salinity Stress
Abstract
Acetylation in histone and non-histone proteins is balanced by histone acetyltransferase and histone deacetylase (HDAC) enzymatic activity, an essential aspect of fine-tuning plant response to environmental stresses. HDACs in Arabidopsis are composed of three families (RPD3-like, SIRT, and HD-tuins). A previous study indicated that class I (HDA19) and class II (HDA5/14/15/18) RPD3-like family HDACs control positive and negative responses to salinity stress, respectively. Furthermore, quintuple hda5/14/15/18/19 mutants (quint) exhibit salinity stress tolerance, suggesting that hda19 suppresses the sensitivity to salinity stress present in quadruple hda5/14/15/18 mutants (quad). In the present study, transcriptome analysis of the quint mutant was conducted to elucidate the hierarchical control of salinity stress response operated by RPD3-like family HDACs (HDA5/14/15/18/19). The analysis identified 4,832 salt-responsive genes in wild-type (Col-0), hda19-3, quad, and quint plants and revealed that 56.7% of the salt-responsive genes exhibited a similar expression pattern in both the hda19-3 and quint plants. These results indicate that deficiency in HDA19 has a bigger impact on salinity stress response than in class II HDACs. Furthermore, the expression pattern of genes encoding enzymes that metabolize phytohormones raises the possibility that a drastic change in the homeostasis of phytohormones, such as abscisic acid, brassinosteroid, and gibberellin, may contribute to increasing stress tolerance in hda19-3 and quint plants. Among these phytohormones, abscisic acid accumulation actually increased in hda19-3 and quint plants, and decreased in quad, compared with wild-type plants. Importantly, 7.8% of the salt-responsive genes in quint plants exhibited a similar expression pattern in quad plants, suggesting that some gene sets are regulated in an HDA5/14/15/18-dependent manner. The transcriptome analysis conducted in the present study revealed the hierarchical and independent regulation of salt stress response that is mediated through HDA19 and class II HDACs.
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