CsMYB96 confers water loss resistance in citrus fruit by simultaneous regulation of water transport and wax biosynthesis.

A citrus R2R3 MYB transcription factor (CsMYB96) was found to alleviate water loss by simultaneously regulating plasma membrane intrinsic proteins (CsPIPs) and wax-related genes. Expression profiling indicated that CsPIP1;1 and CsPIP2;4 are representative aquaporins with high expression, and are down-regulated in the peel of postharvest citrus fruit. CsPIP2;4 was further characterized as the predominant CsPIP with high expression and high-water channel activity. Besides, transient overexpression of CsPIP2;4 accelerated the water loss of citrus fruit. The in silico analysis further revealed that the expression of CsMYB96 had a significant negative correlation with that of CsPIPs. In vivo and in vitro experiments confirmed that CsMYB96 can directly repress the expression of CsPIPs. Furthermore, CsMYB96 can activate the wax-related genes and promote wax biosynthesis for defense against water loss. The transient and stable overexpression of CsMYB96 reduced the water loss of citrus fruit and Arabidopsis.