Melatonin treatment accelerates yam tuber healing through promoting the biosynthesis and polymerization of suberin polyaliphatic monomers at wound sites

BACKGROUND Suberin polyaliphatics (SPA) deposited at wound sites can facilitate yam tuber healing. However, the effect of melatonin (MT) on wound healing of yam tuber in relation to SPA formation remains unknown. RESULTS MT treatment significantly increased SPA deposition and reduced weight loss, disease index and malondialdehyde (MDA) content compared to control, supporting the effective role of MT in accelerating yam tuber healing. MT up‐regulated expression of SPA monomer biosynthetic genes, including β‐ketoacyl CoA synthases ( DoKCS2 and DoKCS6 ), fatty acid ω‐hydroxylases ( DoCYP86A1 and DoCYP86B1 ), feruloyl‐CoA transferase ( DoFHT ), glycerol 3‐phosphate acyltransferases ( DoGPAT5 and DoGPAT7 ) and activated their enzyme activity. Gene expression of G‐type ATP‐binding cassette transporters ( DoABCG2 and DoABCG6 ) and GDSL‐type esterase/lipase proteins ( DoGELP38 , DoGELP51 and DoGELP96 ), as well as ABCG content, was increased by MT treatment, which might promote the transport and polymerization of SPA monomers. Moreover, endogenous MT and abscisic acid levels were significantly induced by exogenous MT, which was tightly correlated with SPA‐associated gene expression. CONCLUSION These findings indicate that MT treatment facilitates wound healing of yam tuber through positively regulating SPA formation.