活性氧在热处理诱导香蕉耐冷性中的作用

【目的】探讨活性氧在热处理诱导果实耐冷性中的作用。【方法】采用10 μmol•L-1的活性氧合成酶NADPH氧化酶的专一性抑制剂二苯基碘（diphenylene iodonium, DPI）预处理香蕉果实，然后于52℃热水处理3 min，之后置于7℃低温贮藏，测定冷害指数、叶绿素光化学效率Fv/Fm、过氧化氢（H2O2）和超氧阴离子（ ）含量、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性及其基因表达。【结果】与单独热水处理香蕉果实相比，热处理前预先用DPI处理的香蕉果实具有较高的冷害指数和较低的Fv/Fm值；在冷藏前3 d减少了由热处理导致的H2O2含量和 产生速率的快速积累；降低了CAT和APX的活性；抑制了MaCAT和MaAPX基因的表达。【结论】DPI预处理减少了香蕉果实由于热处理而导致的活性氧的迅速积累，相应地也减弱了热处理诱导的耐冷效果，表现为冷害症状加剧。推测热水处理诱导的早期活性氧爆发为香蕉果实的耐冷诱导所必需，其可能作为信号分子参与了此过程。

The Role of Reactive Oxygen Species in Heat Treatment-Induced Chilling Tolerance in Banana Fruit

【Objective】The objective of this study is to investigate the role of reactive oxygen species (ROS) in heat -induced chilling tolerance in banana fruit.【Method】 In this study, 10 μmol•L-1 diphenylene iodonium (DPI), a NADPH oxidase specific inhibitor, was used to inhibit ROS generation in hot water treated fruits. After heat treatment (52℃ for 3 min), banana fruits were stored at 7℃. The chilling injury index, Fv/Fm, contents of H2O2 and  , activities of catalase (CAT) and ascorbate peroxidase (APX), gene expressions of MaCAT and MaAPX genes were determined.【Result】Compared with heat-treated fruits, fruits treated with DPI prior to heat treatment exhibited higher chilling injury index and lower values of Fv/Fm, Moreover, DPI treatment prevented heat-triggered H2O2 and   accumulation, and inhibited the increase of the activities of CAT and APX, and the expressions of MaCAT and MaAPX genes. 【Conclusion】 It is suggested that pre-treatment with DPI prevented the rapid accumulation of ROS induced by heat treatment, which counteracted heat treatment-induced chilling tolerance accordingly had a negative effect on the chilling tolerance induced by heat treatment and showed serious chilling injury symptoms. The reactive oxygen species induced by heat treatment might serve as signal molecules involving in chilling resistance of banana fruits.