In this study, potato tubers (Solanum tuberosum L.) were artificially damaged and then soaked in 10 mmol/L diethyldithiocarbamate (DDC) solution, an inhibitor of superoxide dismutase (SOD). We determined the StSODs gene expression and activity of SOD, reactive oxygen species (ROS) content, phenylpropanoid metabolism-related enzyme activity, total phenols and lignin contents at the wound site during the healing process. In addition, the deposition of suberin polyphenolic (SPP) and lignin were observed. The results showed that DDC treatment downregulated StSODs expression, suppressed SOD activity, reduced the content of H₂O₂, and decreased the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) as well as the contents of total phenols and lignin compared with the control. After 1 day of healing, the expression of StCSD1, StFSD3 and StMSD in the treated tubers were 31.90%, 69.30% and 61.83% lower than those of the control, respectively. In addition, SOD activity, H₂O₂ content, PAL and POD activity were 36.17%, 15.38%, 28.20% and 24.90% lower than those of the control, respectively. The deposition of SPP and lignin were delayed by DDC treatment. After 7 days of healing, the thicknesses of the SPP and lignin layers in the treated tubers were 16.84% and 23.00% lower than those of the control, respectively. In summary, DDC treatment downregulated StSODs expression during the healing process, inhibited the activity of SOD, reduced H₂O₂ content, weakened phenylpropanoid metabolism, and delayed the accumulation of SPP and lignin at the wound site of potato tubers. Therefore, the effect of DDC on delaying callus formation in wounded potato tubers is closely related to its inhibitory effect on H₂O₂ production catalyzed by SOD.

In this study, artificially wounded potato tubers were treated with 2 mmol/L salicylic acid (SA) for 10 min. Reactive oxygen species (ROS) production and ROS scavenging enzyme activities were determined, and in vitro antioxidant capacity and cell membrane integrity in the wounds were analyzed during the early wound healing (within 12 h after wounding) period. The results showed that SA increased the activities of NADPH oxidase and superoxide dismutase, and promoted the accumulation of superoxide anion radical and H₂O₂ in tuber wounds during the early wound healing period. SA increased the activity of peroxidase, but decreased the activity of catalase. SA also increased the activities of ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase and glutathione reductase, and increased the levels of ascorbic acid and reduced glutathione. In addition, SA treatment improved the capacity to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical and ferric reducing antioxidant power (FRAP) and reduced cell membrane permeability and malondialdehyde (MDA) content. In conclusion, SA could maintain cell membrane integrity and consequently ensure the smooth progress of normal metabolism during early wound healing by regulating ROS homeostasis and improving in vitro antioxidant activity in potato tuber wounds.