Tolerance to chilling injury induced by hot water treatment increases activities of antioxidant enzymes in tomato fruits

Tomato is sensitive to chilling injury (CI) when stored at temperatures below 12°C, and increased evidences showed that CI is associated to oxidative stress. Hot water treatments (HWT) have shown to induce CI tolerance, and it is hypothesised that antioxidant enzymes participate in the induction of CI tolerance. The present work evaluates the effect of a HWT (42°C for 5 min) on CI symptoms, physiological markers related to membrane damage, and the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), in mature-green tomato fruits (cv. Imperial) during 15 d of cold storage at chilling (5°C) and non-chilling (12°C) conditions. The efficiency of HWT to induce CI tolerance in tomato was validated by reductions in CI symptoms severity (CI index). Fruits subjected to HWT and subsequent chilling conditions presented reduced membrane damage (electrolyte leakage) and lipid peroxidation (malondialdehyde content). Furthermore, HWT increased the activities of SOD, CAT, and APX during the storage at 5°C, suggesting that higher antioxidant enzymes activity may be providing protection against lipid membrane peroxidation during cold storage, thus, inducing CI tolerance.