ABSTRACT

Histone acetyltransferase (HAT) and histone deacetylase (HDAC) family members control histone acetylation levels to regulate gene expression and play significant roles in microbe interactions and abioticstress responses. However, the HAT and HDAC family members in citrus have not yet been identified, and their responses to drought (abiotic stress) and arbuscular mycorrhizal fungi (AMF) colonization, remain unknown. In the present study, HAT and HDAC family genes were characterized in the citrus genome. A total of 14 CsHATs and 11 CsHDACs were identified in the citrus genome, of which 8 CsHATs and 7 CsHDACs showed syntenic relationships with Arabidopsis HATs and HDACs, respectively. Furthermore, the 14 CsHATs were classified into GNAT-MYST, TAFII250, MYST, CBP, and one citrus-unique family. The 11 CsHDACs were classified into SIR2, HD2, and RPD3/HDA1. Gene expression analysis showed AMF colonizationor drought induced the expression of CsHAT1, 2, 6, 7, 9, 11, 12, and 14, and repressed CsHDAC1, 2, 5, 6, 8, and 10. The regulation of HAT and HDAC expression was not always consistent with the cis-elements identified in their promoters. The present study offers useful insights into the citrus HAT and HDAC gene families and their expression in response to AMF colonization and drought stress.