Exogenously applied abscisic acid accelerates wound healing of Chinese yam tubers (Dioscorea opposita) through promoting suberin polyphenolics biosynthesis

Abstract

Water loss, nutrient elution and pathogen attacks caused by mechanical wounding are the primary sources of postharvest loss of fruit and vegetables. Continuously increasing information has unraveled that abscisic acid (ABA) can accelerate wound healing of fruit and vegetables via stimulating suberin polyphenolics (SPP) biosynthesis, whereas the effect of ABA in wound healing of Chinese yam tubers remains unclear. The treatment of ABA and fluridone (FLD, an inhibitor of ABA biosynthesis) on postharvest wound healing of yam tubers was investigated in this study. The results showed that ABA treatment facilitated wound healing process of yam tubers, representing by the reduced weight loss and relative electrolyte leakage (REL). ABA enhanced the expression levels of phenylalanine ammonialyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL), as well as the corresponding enzyme contents and activities. Correspondingly, the contents of major monomers such as ferulic acid, caffeic acid and p-coumaric acid also increased. Simultaneously, ABA could improve the expression of peroxidase (POD), the enzyme content and activity, as well as hydrogen peroxide (H2O2) production, which might contribute to the polymerization of SPP and lignin. Inversely, inhibition of ABA production by FLD application displayed an opposite effect to ABA treatment. These results demonstrate that application of ABA stimulated wound healing of Chinese yam tubers via improving the gene expressions of relevant enzymes, their contents and activities, so that maintain high quality of postharvest yam tubers.