腐胺增强香蕉果实低温耐受性的作用机制

Mechanism of putrescine in increasing chilling tolerance of postharvest banana fruit

为了研究腐胺在采后香蕉果实低温耐受性中的作用及其作用机制,通过外源施加的方式,研究腐胺对采后香蕉果实的低温耐受表型、冷害指数、细胞膜完整性、膜脂过氧化程度、脂肪氧化酶活性及内源一氧化氮含量的影响。结果表明,低浓度的腐胺能够增强采后香蕉果实的低温耐受性,其中以5 mmol/L的效果最好。5 mmol/L的腐胺显著降低了7℃环境下香蕉的冷害指数和膜脂过氧化程度,有效维持细胞膜的完整性,而一氧化氮专一性清除剂抑制了腐胺对冷害指数的降低。初步研究其作用机制为:抑制了由低温导致的脂肪氧化酶活性的升高,表明信号分子一氧化氮在腐胺增强采后香蕉果实的低温耐受性过程中发挥关键作用。

To study function and mechanism of putrescine(Put) on chilling tolerance of postharvest banana fruit, the effects of exogenous Put on chilling tolerance phenotype, chilling injury index, integrity of cell membrane, membrane lipid peroxidation, lipoxygenase activity and endogenous nitric oxide content were investigated. The result showed that Put at low concentration induced chilling tolerance of postharvest banana fruit significantly and the optimal concentration is 5 mmol/L. Put of 5 mmol/L decreased chilling injury index, membrane lipid peroxidation and maintained integrity of cell membrane dramatically.Moreover, nitric oxide is involved in the process of Put-induced chilling tolerance of postharvest banana fruit because cPTIO, a nitric oxide scavenger, inversed the effect of Put. The mechanism is that Put inhibited chilling-induced lipoxygenase activity, showing exogenous Put increased chilling tolerance of postharvest banana fruit by inducing endogenous content of nitric oxide.