Chlorine Dioxide Accelerates the Wound Healing Process of Potato Tubers by Eliciting Phenylpropanoid Metabolism

Chlorine dioxide (ClO₂) is a safe and effective disinfectant that is widely used for preserving fruits and vegetables as well as controlling microorganisms. However, the mechanism by which ClO₂ treatment affects wound healing in potato tubers remains unclear. The half cut potato tubers ‘cv. Atlantic’ were soaked with 25 mg/L ClO₂ for 10 min, which were stored for 0, 3, 5, 7, 14, and 21 d at room temperature in dark for wound healing. The mass loss rate and the disease index of wounded tubers inoculated with Fusarium sulphureum were determined, the deposition of suberin poly phenolic (SPP) and lignin at wound sites were observed, and the activities of the key enzymes of phenylpropanoid metabolism and peroxidase (POD) as well as the content of phenylpropanoid metabolism products and H₂O₂ at wound sites were measured. This result showed that ClO₂ at 25 mg/L accelerated SPP and lignin deposition and increased cell layer thickness at wounds. Furthermore, the mass loss rate and disease index (after inoculated with F. sulphureum) of potato tubers significantly was reduced by 20.8% and 45.3%, respectively, on day 14 after ClO₂ treatment. Additionally, ClO₂ enhanced the contents of five phenolic acids (cinnamic, p-coumaric, caffeic, ferulic, and sinapic acids) and three lignin monomers (p-coumaryl, sinapyl, and coniferyl alcohols) by increasing phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD) activities. Moreover, ClO₂ treatment significantly promoted the synthesis of total phenolics, flavonoids and lignin and elevated H₂O₂ content and peroxidase activity. In conclusion, ClO₂ treatment accelerated the deposition of SPP and lignin at wound sites, decreased the mass loss rate and disease index of damaged potato tubers during healing, triggered the phenylpropanoid metabolism pathway, and increased H₂O₂ content and POD activity. These findings provide evidence that ClO₂ treatment can accelerate wound healing in potato tubers.