Histone deacetylase VlSRT1 represses the regulation of VlERF95-mediated transcriptional activation during rachis browning in grape

Rachis browning adversely affects the appearance quality and commodity value, thus paring down consumer acceptability. A certain cognition on browning mechanism has been made after years of research. But how to modulate transcription of downstream genes via mechanisms mediated by histone acetylation modification in this regard is not yet clear. In this study, a histone deacetylase, VlSRT1, of grape rachis was found to contribute to the transcriptional modification of histone H3 acetylation in ethylene signal transduction. Physical interaction between VlSRT1 and VlERF95 was confirmed both in vivo and in vitro. In the presence of 1-MCP, increased VlSRT1 brings about a reduction of histone H3ac abundance at the site adjacent to the VlERF95-binding site in the promoter of VlERF95-targeted genes VlACS5 and VlPAO1, and negatively regulates ethylene biosynthesis and Chlorophyll degradation. This indicates that VlSRT1 might be recruited by VlERF95 into the promoters of VlACS5 and VlPAO1 to form a complex, which impairs the transcriptional activation of VlACS5 and VlPAO1, thereby retarding the progression of browning and senescence in rachis. Chromatin immunoprecipitation of acetylated histone H3 on the promoters of VlACS5 and VlPAO1 further validated the effect of ethylene on acetylation levels. Our results enrich new mechanisms of epigenetic regulation in ethylene signal transduction in grape and provide new research ideas for understanding the occurrence of rachis browning and the anti-browning role of 1-MCP in preserving rachis freshness after harvest.