Abstract: 【Objective】The objective of this study is to find out the differences of tuber healing ability of resistant and susceptible potato cultivars against dry rot (‘Qingshu No. 168’ and ‘Longshu No. 3’), and explore the reasons causing differences in the levels of lignin and suberin accumulation and phenylpropanoid metabolism.【Method】The resistant cultivar ‘Qingshu No. 168’ and susceptible cultivar ‘Longshu No. 3’ were used as materials. The damage of tubers was artificially simulated and heal was conducted at ambient temperature. The healing effect was assessed by determining the weight loss and disease index of wounded tubers that were inoculated with Fusarium sulphureum at every healing time point. Phloroglucinol-HCl staining and toluidin blue O-neutral red staining were used to observe lignin and suberin deposition, and the lignified cell layers and suberin fluorescent intensity were quantified. Moreover, the key enzyme and metabolites of phenylpropanoid metabolism pathway such as phenylalanine ammonia lyase activity, and the contents of lignin, total phenol and flavonoid were determined to compare the differences of healing ability between the two cultivars.【Result】The weight loss of ‘Qingshu No. 168’ was significantly lower than that of ‘Longshu No. 3’ during healing. The weight loss of ‘Qingshu No. 168’ and ‘Longshu No. 3’ was 0.93% and 1.96% after 14 days of healing, and the weight loss of ‘Qingshu No. 168’ was 52.3% lower than that of ‘Longshu No. 3’. The disease index of ‘Qingshu No. 168’ was also significantly lower than ‘Longshu No. 3’ after inoculated with F. sulphureum during healing. After 3 days of healing for inoculated tubers, the disease index of ‘Qingshu No. 168’ and ‘Longshu No. 3’ was 20.36 and 71.59, respectively, the former was 71.5% lower than the later. During healing, ‘Qingshu No. 168’ had higher accumulation rate of lignin and suberin than ‘Longshu No. 3’. After healing for 14 days, the thickness of lignified cell layers and total fluorescent intensity of suberin of ‘Qingshu No. 168’ were 47.4% and 60.6% higher than ‘Longshu No. 3’. In addition, ‘Qingshu No. 168’ showed more phenylpropanoid metabolism activity than ‘Longshu No. 3’. The activity of phenylalanine ammonialyase and the lignin content of ‘Qingshu No. 168’ were 77% and 65% higher than ‘Longshu No. 3’after healing for 14 days, respectively. The total phenolics contents of the two cultivars showed a significant difference at late stage of healing, ‘Qingshu No. 168’ was 76% higher than ‘Longshu No. 3’ after healing for 14 days. However, no significant difference was found in the flavonoids content between the two cultivars during healing.【Conclusion】The resistant cultivar ‘Qingshu No. 168’ showed stronger healing ability than susceptible cultivar ‘Longshu No. 3’. A stronger healing ability of resistant cultivar is related with its higher phenylpropanoid metabolism activity.

Key words: potato, cultivars, tuber, wound healing, phenylpropanoid metabolism