青香蕉和黄熟香蕉果皮感病过程中5种酶活性的变化

以同一品种的未后熟的青香蕉和已黄熟的香蕉为材料,测定了接种炭疽病菌5d内果皮PPO、POD、SOD、PAL和LOX活性的变化,探讨与香蕉抗病性相关的酶类。结果表明,不论接种与否,青香蕉果皮中的PPO、POD和SOD的活性明显低于黄熟香蕉,而PAL和LOX活性高于黄熟香蕉;接种对PPO、POD和LOX活性影响不大,但引起SOD和PAL活性下降。青香蕉果皮中较低的PPO、POD和SOD的活性有利于活性氧和酚类物质的积累而产生过敏性反应,较高的PAL和LOX活性则利于苯丙烷类代谢和脂质过氧化,有利于抗病物质的形成。PAL和LOX是香蕉抗病性形成的关键酶。

Activity changes of five enzymes in green maturing and yellow ripening banana fruit infected with Colletotrichum musae

The disease resistance of banana fruit is gradually reduced during ripening. In order to study the disease resistance related enzymes,polyphenol oxidase(PPO),peroxidase(POD),superoxide dismutase(SOD),phenylalanine ammonia lyase(PAL) and lipoxygenase(LOX) in two ripening stages of banana fruit, green maturing and yellow ripening,infected with Colletotrichum musae were investigated and studied during 5 days. No mater whether these banana fruit were inoculated or not, the activities of PPO, POD and SOD were lower but the activities of PAL and LOX were higher in the skins of green maturing banana skins than that in the skins of yellow ripening ones. In both ripening stage fruit, inoculation with C. musae resulted in the decreases in the activities of SOD and PAL,but did not affect the activities of PPO,POD and LOX. The lower level of PPO,POD and SOD activities might cause the accumulation of active radicals and phenolic materials, which lead to the hypersensitive reaction. The higher level of PAL and LOX activities might be advantageous to the phenyl propanes metabolism,lipid peroxidation and the formation of antibiotic substances. PAL and LOX might be the key enzymes of disease resistance in banana fruit.