Membrane lipid metabolism of postharvest banana under anthracnose stress

【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 phospholipidphosphatidylcholine(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.