Histone deacetylase HDA9 negatively regulates salt and drought stress responsiveness in Arabidopsis

Abstract

Histone modification is an important epigenetic regulation in higher plants adapting to environment changes including salt and drought stresses. In this report, we show that the Arabidopsis RPD3-type histone deacetylase HDA9 is involved in modulating plant responses to salt and drought stresses in Arabidopsis. Loss-of-function mutants of the gene displayed phenotypes (such as seedling root growth and seed germination) insensitive to NaCl and polyethylene glycol (PEG) treatments. HDA9 mutation led to up-regulation of many genes, among which those involved in response to water deprivation stress (GO: 0009414) were enriched. These genes were much more induced in the mutants than wild-type plants when treated with PEG and NaCl. In addition, we found that in the mutants, salt and drought stresses led to much higher levels of histone H3K9 acetylation at promoters of 14 genes randomly selected from those that respond to water-deprivation stress than in wild-type plants. Our study suggested that HDA9 might be a novel chromatin protein that negatively regulates plant sensitivity to salt and drought stresses by regulating histone acetylation levels of a large number of stress-responsive genes in Arabidopsis.

The Distinct Roles of Class I and II RPD3-Like Histone Deacetylases in Salinity Stress Response

“…Currently, however, there is no evidence demonstrating that recipient organisms use naturally produced HDIs from donor organisms to enhance stress tolerance. This and previous studies (Sako et al, 2016;Zheng et al, 2016) raise the possibility of the existence of HDI-mediated, symbiotic relationships that enhance abiotic stress tolerance. Further studies are necessary to elucidate the role of naturally produced metabolites with HDI properties in natural habitats.…”

“…However, it is possible that each HDAC may control the response to salt stress in a different manner among class I HDACs. hda9 and hda19 knockdown lines lead to the derepression of salt stress-responsive genes (Mehdi et al, 2016;Zheng et al, 2016). Considering the previous results from the functional analysis of HDA9 and the hda19 mutants in this study, both of which belong to class I HDACs, HDA9 and HDA19 negatively regulate salt stress-responsive genes.…”

“…Considering the previous results from the functional analysis of HDA9 and the hda19 mutants in this study, both of which belong to class I HDACs, HDA9 and HDA19 negatively regulate salt stress-responsive genes. In contrast to these two class I HDACs, HDA6 appears to positively regulate the salt response , although HDA6 often acts redundantly with HDA19 (Kim et al, 2012) and HDA9 also interacts with both of them (Zheng et al, 2016). Previous biochemical studies revealed that HDA19/AtHD1, HDA5, HDA6, and HDA15 possess HDAC enzyme activity and that their activities are inhibited by TSA in RPD3-like HDACs (Earley et al, 2006;Fong et al, 2006;Liu et al, 2013;Luo et al, 2015).…”

“…The involvement of HDACs in response to salinity stress also has been documented. For example, HDA9 and HD2D negatively regulate the salt response (Han et al, 2016;Zheng et al, 2016), whereas HDA6 and HD2C positively regulate it Luo et al, 2012). In the case of HDA19, previous studies reported controversial data demonstrating that an hda19 knockout mutant in the Wassilewskija (Ws) background shows sensitivity to salt stress, whereas an hda19 knockdown mutant in the Columbia-0 (Col-0) background exhibits the opposite phenotype Mehdi et al, 2016).…”

POWERDRESS and HDA9 interact and promote histone H3 deacetylation at specific genomic sites in Arabidopsis

“…HDA9 regulates several biological processes, such as flowering time, seed dormancy, and stress responses (14,35,36,40,41). Although previous studies have shown that development and stress-response genes are up-regulated and this is accompanied by hyperacetylation in the hda9 mutant, there have been no reports about HDA9-interacting proteins required for its histone deacetylation function.…”