Histone deacetylase HDA710 controls salt tolerance by regulating ABA signaling in rice

Plants have evolved numerous mechanisms that assist them in withstanding environmental stresses.Histone deacetylases(HDACs)play crucial roles in plant stress responses;however,their regulatory mechanisms remain poorly understood.Here,we explored the function of HDA710/OsHDAC2,a member of the HDAC RPD3/HDA1 family,in stress tolerance in rice(Oryza sativa).We established that HDA710 localizes to both the nucleus and cytoplasm and is involved in regulating the acetylation of histone H3 and H4,specifically targeting H4 K5 and H4 K16 under normal conditions.HDA710 transcript accumulation levels were strongly induced by abiotic stresses including drought and salinity,as well as by the phytohormones jasmonic acid(JA)and abscisic acid(ABA).hda710 knockout mutant plants showed enhanced salinity tolerance and reduced ABA sensitivity,whereas transgenic plants overexpressing HDA710 displayed the opposite phenotypes.Moreover,ABAand salt-stress-responsive genes,such as OsLEA3,OsABI5,OsbZIP72,and OsNHX1,were upregulated in hda710 compared with wild-type plants.These expression differences corresponded with higher levels of histone H4 acetylation in gene promoter regions in hda710 compared with the wild type under ABA and salt-stress treatment.Collectively,these results suggest that HDA710 is involved in regulating ABA-and salt-stress-responsive genes by altering H4 acetylation levels in their promoters.