炭疽病胁迫下采后香蕉的膜脂代谢

Membrane lipid metabolism of postharvest banana under anthracnose stress

【目的】从细胞膜降解角度研究芭蕉炭疽菌(Colletotrichum musae)采后侵染香蕉果实的机制,为进一步研究香蕉炭疽病及其防控措施提供理论依据。【方法】以桂蕉6号香蕉为试验材料,采用喷雾接种芭蕉炭疽菌侵染香蕉果实,以果实喷雾蒸馏水作对照,每3 d取样1次,通过测定采后贮藏过程中香蕉果实的病情指数、果实硬度及果皮电导率、细胞膜降解关键酶活性、细胞膜磷脂和脂肪酸组分与含量的变化规律,明确炭疽菌侵染对香蕉果皮膜脂代谢的影响。【结果】接种芭蕉炭疽菌可促进香蕉果实炭疽病的发生,病情指数随贮藏时间的延长而增加,同时果实硬度下降、果皮电导率升高,贮藏至第15 d,炭疽菌侵染组与对照组相比,果实的病情指数显著增加61.31%(P<0.05,下同)、果实硬度显著下降35.79%、果皮电导率显著升高27.94%。炭疽菌侵染促进香蕉果皮膜脂代谢相关酶[磷脂酶C(PLC)、磷脂酶D(PLD)和脂氧合酶(LOX)]活性增强,贮藏至第15 d,炭疽菌侵染组的果皮PLC、PLD和LOX活性较对照组分别显著提高31.21%、63.72%和26.24%;同时炭疽菌侵染加速果皮细胞膜磷脂[磷脂酰胆碱(PC)、磷脂酰肌醇(PI)和磷脂酰乙醇胺(PE)]降解为磷脂酸(PA)、不饱和脂肪酸(油酸、亚油酸和亚麻酸等)氧化为饱和脂肪酸(棕榈酸和硬脂酸等),贮藏至第15 d,与对照组相比,炭疽菌侵染组的果皮不饱和脂肪酸总量降低12.97%,饱和脂肪酸总量则提高17.77%。炭疽菌侵染促进香蕉果皮氧化,贮藏至第15 d,炭疽菌侵染组的丙二醛(MDA)和过氧化氢(H2O2)含量较对照组分别提高17.23%和13.58%。【结论】炭疽病菌侵染与贮藏期间香蕉果皮细胞膜脂代谢有关,炭疽菌侵染加剧细胞膜水解,导致细胞膜结构破坏和功能丧失,从而促使炭疽病发生。

【Objective】The mechanism of Colletotrichum musae infection in banana fruits after harvest was studied from the perspective of cell membrane degradation,which provided theoretical basis for further study of banana anthracnose and its prevention and control measures.【Method】The banana variety Guijiao 6 was used as the raw material,banana fruits were inoculated with C.musae by spray,and spraying distilled water was control,and sampled once every 3 d.The effects of C.musae infection on lipid metabolism of banana peel membrane were studied by measuring the disease index,fruit hardness,conductivity rate,distilled water rate,the activities of key enzymes in cell membrane metabolism,the composition and content of phospholipids and fatty acids in cell membrane during postharvest storage of banana fruits.【Result】Inoculation of C.musae could promote the occurrence of anthracnose,and the disease index increased with the prolonging of storage time,while the fruit hardness decreased and conductivity rate increased.On day 15 of storage,the disease index of the anthrax infected group significantly increased by 61.31%(P<0.05,the same below),the fruit hardness decreased by 35.79%,and the peel conductivity rate increased by 27.94%compared with the control group.C.musae infection promoted the banana peel membrane lipid metabolism related enzymes phospholipase C(PLC),phospholipase D(PLD),lipoxygenase(LOX)activities.On the day 15 of storage,the activities of PLC,PLD and LOX in banana peel were 31.21%,63.72%and 26.24%higher than those in the control group respectively.At the same time,C.musae infection accelerated peel cell membrane phospholipid[phosphatidylcholine(PC),phosphatidylinositol(PI)and phosphatidylethanolamines(PE)]degradation to phosphatidic acid(PA),and accelerated unsaturated fatty acids(oleic acid,linoleic acid and linolenic acid)oxidation to saturated fatty acid(palmitic acid and stearic acid).On the day 15 of storage,the total amount of unsaturated fatty acids in banana peel decreased by 12.97%and the total amount of saturated fatty acids increased by 17.77%compared with the control group.Anthracnose infection promoted oxidation of banana peel.The contents of malonaldehyde(MDA)and hydrogen peroxide(H2O2)in anthracnose infection group were 17.23%and 13.58%higher than those in control group,respectively.【Conclusion】Anthracnose infection is related to lipid metabolism of pericarp membrane during banana storage.The cell membrane hydrolysis is enhanced and lead to cell membrane structure destruction and function loss,prompting anthracnose.