Abstract: Objective: To study the effect of postharvest nitric oxide (NO) treatment on wound healing in potato tubers, and to partially explore the underlying mechanism. Methods: Potato tubers of the cultivar ‘Longshu 7’ were artificially wounded, dipped with sodium nitroprusside (SNP) as an exogenous donor of NO at 0.5 mmol/L for 10 minutes, and then allowed to heal at ambient temperature in darkness. The mass loss rate of wounded tubers and the disease index of those inoculated with Fusarium sulphureum were measured during the healing period, and the accumulation of suberin and lignin was observed in the wounds. Phenylpropanoid metabolism and peroxidase activity as well as H2O2 content in the wounds were also analyzed. Results: The mass loss rate of wounded tubers and the disease index of inoculated tubers were significantly reduced by NO treatment during healing period, which were 43.5% and 27% lower than that of the control on day 7 of healing. The treatment accelerated the accumulation of polyphenol suberin, polyaliphatic suberin and lignin, increasing the thickness of the polyphenol suberin, polyaliphatic suberin and lignin layers by 25.2%, 27.3% and 23.6% relative to the control on day 7, respectively. Also, the treatment increased phenylalanine ammonia-lyase activity, and the contents of total phenols, flavonoids and lignin in the wounds by 75.3%, 31%, 39.6% and 32.8% compared with those of the control on day 14, respectively. In addition, NO increased significantly peroxidase activity and hydrogen peroxide content (P < 0.05). Conclusion: NO treatment can activate phenylpropane metabolism, improve peroxidase activity and H2O2 content, and accelerate suberin and lignin accumulation in the wounds, thereby promoting wound healing in potato tubers.

Key words: potato tubers; nitric oxide; wound healing; phenylpropane metabolism