Hot Water Treatment Delays Ripening-associated Metabolic Shift in 'Okrong' Mango Fruit during Storage

Effects of hot water treatment (HWT) on metabolism of mango (Mangifera indica cv. Okrong) fruit during low-temperature storage (LTS) and subsequent room temperature fruit ripening (RTFR) were examined. Mature-green 'Okrong' mango fruit were treated by immersing in hot (50 +/- 1 degrees C) or ambient (30 +/- 1 degrees C) water for 10 min, stored either at 8 or 12 degrees C for 15 days, followed by transfer to room temperature (30 +/- 2 degrees C) for 5 days. Rate of ethylene production was significantly reduced by HWT during LTS and RTFR in all treatments. HWT increased catalase activity, suppressed ascorbate peroxidase activity, and had no effect on glutathione reductase activity during the ripening phase but showed a slight stimulatory effect during LTS. HWT altered RNA transcripts of manganese-superoxide dismutase, pectate lyase, beta-galactosidase, and beta-1,3-glucanase, which exhibited increases during LTS. RTFR of LTS fruit caused reduction in transcript levels of these genes, except pectate lyase. Total protein patterns were altered by all treatments during LTS and RTFR, but HWT arrested loss of several proteins during RTFR. Taken together, results provide strong evidence that HWT increases the storage period of mango by extending fruit shelf life through the regulation of a myriad of metabolic parameters, including patterns of antioxidant and cell wall hydrolase genes and protein expression during storage at low and ambient temperatures.