Genome-wide characterization of the CsGPAT gene family and functional insights into citrus fruit wound healing

Postharvest citrus fruit are susceptible to mechanical damage, and wound healing via suberin deposition provides a critical physical barrier against pathogen invasion. Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first step in suberin biosynthesis by acylating glycerol-3-phosphate to lysophosphatidic acid, but GPAT genes' roles in citrus wound healing remain unclear. In this study, eight CsGPATs were identified in citrus, in which the functions of CsGPAT2, CsGPAT3 and CsGPAT4 were mainly analyzed. Changes in suberin content in citrus wounds after transient overexpression and virus-induced gene silencing (VIGS) of the CsGPATs were observed by orthogonal fluorescence microscopy. Meanwhile, the growth of green mold on citrus fruit was observed, and GPAT enzyme activity was measured. Overexpression of the CsGPATs significantly improved wound healing, decreased green mold incidence and lesion diameter, and significantly increased GPAT enzyme activity. The GC-MS analysis indicated that the transient overexpression of the CsGPATs promoted the accumulation of suberin monomers. In addition, the expression levels of key genes involved in the suberin synthesis pathway were notably elevated. In conclusion, CsGPATs facilitated suberin accumulation, which enhanced wound healing and effectively suppressed green mold development in citrus fruit. This research offers novel perspectives on the regulatory mechanisms underlying wound healing, which are pivotal for enhancing the postharvest quality of citrus fruit.