Exogenous methyl jasmonate promotes wound healing of Chinese yam tubers (Dioscorea opposita) through the deposition of suberin polyaliphatics at the wound sites

Suberin polyaliphatics (SPA) is an important component of suberin, which plays a pivotal role in controlling water loss and solute fluxes during wound healing of fruit and vegetables. The objective of this study was to investigate the effect of exogenous methyl jasmonate (MeJA) on wound-induced SPA deposition in Chinese yam tubers. The results exhibited that MeJA treatment accelerated the deposition of SPA and the wound healing process. The gene expressions of 8-ketoacyl-CoA synthases (DoKCS2, DoKCS6), CYP86 subfamily of cytochrome P450 monooxygenases (DoCYP86A1, DoCYP86B1) and Glycerol-3-phosphate acyltransferases (DoGPAT5, DoGPAT7) and their corresponding protein content (i.e. KCS, CYP, GPAT) associated with SPA monomer biosynthesis were notably increased by MeJA application. Meanwhile, MeJA also enhanced gene expressions of ATP-binding cassette transporter subfamily G proteins (DoABCG2, DoABCG6) and GDSL-type esterase/lipases (DoGELP38, DoGELP51, DoGELP96) and increased ABCG content, which might participate in the trafficking and polymerization of SPA monomer. Noteworthily, application of diethyldithiocarbamic acid (DICA), an inhibitor of jasmonic acid (JA) synthesis, showed an opposite effect to MeJA treatment. These results suggest that MeJA could promote SPA deposition by positively regulating relevant gene expression and corresponding protein content, thereby accelerating wound healing of Chinese yam tubers.