The Mechanism Study Of Sodium Hydrogensulfide Induced Chilling Resistance Of Postharvest Banana Fruit

Chilling injury is one of the most serious problems which could cause losses of chilling sensitive fruit and vegetables in the process of storage, transportation and packaging. Banana fruit is a typical kind of chilling sensitive fruit and is very susceptible to chilling injury during storage below11℃. Consequently, the research on cold damage control technology of banana fruit, extending the life of low temperature storage period and shelf life is of great significance. Hydrogen sulfide (H2S) was considered to be the third gas messenger after nitric oxide (NO) and took participate in various plant physiological processes, similar to the NO. Recent results indicated that appropriate concentration of H2S could regulate stomatal closure, attenuate of abiotic stress injury and involved in regulation of plant senescence. In order to further understanding the effects of exogenous sodium hydrosulfide (NaHS) on chilling injury, changes of quality, antioxidant capacity, proline acumulation, energy metabolism were investigated in banana fruit at7℃(chilling temperature) and then transferred to20℃(room temperature) in this paper. The main results were as follows:(1) At the14th day of the storage, the chilling injury index of banana fruit treated with NaHS was17.75%, respectively, lower than those of the control. Compared with the control fruit, NaHS treatment significantly kept better color and firmness, inhibited ethylene production, delayed the increase of membrane permeability and malondialdehyde (MDA) content, reduced superoxide anion (O2-) and hydrogen peroxide (H2O2) to lower levels, which showed that NaHS treatment could effectively alleviate chilling injury in banana fruit during storage under chilling stress and thus maintained banana fruit better guality during storage.(2) Compared with the control fruit, NaHS treatment obviously increased activities of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), glutathione reductase (GR), superoxide dismutase (SOD) and phenylalamine ammonia-lyase (PAL), maintained higher total antioxidant capacity, enhanced the accumulation of total phenolics and increased glutathione (GSH) content, which can effectively eliminate reactive oxygen species (ROS) to protect cells from damage.(3) Compared with the control fruit, NaHS treatment significantly enhanced the accumulation of proline, which resulted from the increased activities of△1-pyrroline-5-carboxylate synthetase (P5CS) and Ornithine-δ-aminotransferase (OAT) and decreased proline dehydrogenase activity (PDH), thus enhanced stress resistence of banana fruit.(4) NaHS treatment enhanced the content of ATP and ADP, inhibited the increase in AMP and the decrease in energy charge. NaHS treatment also increased activities of cytochrome oxidase (CCO), inhibited activities of succinatedehydrogenase (SDH), H+-ATPase and Ca2+-ATPase to lower levels. It was showed that NaHS treatment could keep higer activities of respiratory enzymes and energy level, which could alleviate chilling injury in banana fruit during storage.