Effect Of No And N₂O On Chilling Injury And Volatiles Of Harvested Banana Fruit

Banana, one of the main fruits in Southern China, is a typical climacteric fruit that issensitive to low temperature. If the fruit suffers the temperature under11-13℃duringstorage and transportation, chilling injury will occur and cause huge economic loss. It havebeen documented that postharvest NO and N₂O application delayed ripening of fruits andvegetables, enhanced its resistance to stress by inhibiting ethylene biosynthesis, extendedthe shelf-life, improved its postharvest quality. Moreover, little report on exogenous NOand application to alleviate chilling injury of banana fruits during storage was found. Thisarticle studied the mechanisms of alleviating chilling injury by NO and N₂O treatment inpostharvested banana fruit from three aspects and also studied effects of NO treatment onaroma formation of banana after chilling stress. The main results are as follows:1. NO and N₂O treatment decreased the MDA content and electrolyte leakage ofcold-stored banana fruit compared to untreated controls. NO treament increased theactivities and gene expression of SOD, CAT, APX, and POD and N₂O treament enhancedthe activities and gene expression of SOD and POD under chilling stress, which mayaccount for the lower levels of O2-· and H2O2, Thus, lipid peroxidation and membrancedamage were reduced and the stability of cell membranes was maintained by NO and N₂Otreatment, which led to an increase in chilling tolerance.2. Activities of LOX, PAL, PPO and gene expression of MaLOX, MaPPO wereinhibited by NO and N₂O treatment. NO treatment reduced gene expression of MaPAL1and MaPAL2. While gene expression of MaPAL1and MaPAL2were up-regulated with N₂Otreatment.3. Gene expression of MaACO, MaEIL1, MaEIL2, of MaEIL4and MaERS familieswere down-regulated and MaACS gene expression was up-regulated with N₂O treament.While gene expression of MaACO was down-regulated before4days, then wasup-regulated. Gene expression of MaEIL1, MaEIL2and of MaEIL4family wereup-regulated before5days, then were down-regulated. Gene expression of MaACS and MaERS family were down-regulated with NO treatment.4. NO treatment inhibited the content of ethanol, ethyl acetate, isoamyl acetate,isobutyl acetate, isoamyl butyrate, E-2-hexenal; NO treatment delayed the expression peakof genes related with aroma metabolism, but didn’t affect the expression of MaLOX、MaHPL、MaPDC、MaBCAT in ripening process.