Effects Of Ginkgo Biloba L. Leaves Extracts Against Phytopathogen In ‘Qinmei’ Kiwifruit Storage

Kiwifruit is a climacteric berry that is very sensitive to ethylene. Physical damage and pathogenic fungus caused by shipping increases the respiration rate and ethylene production of kiwifruit, which results in shortening shelf-life of the product. Therefore, this study aims to investigate the mechanism of Ginkgo biloba leaves against fungus during storage of ‘Qinmei’ kiwifruit, and total flavonoids used as target active ingredient of extracts of Ginkgo biloba leaves(GBE). By morphological and ribosomal r DNA- Internal transcribed spacer(ITS) sequence analysis to identify the fungus during storage of ‘Qinmei’ kiwifruit; the efficacy based on GBE at four different concentrations in maintaining the quality of kiwifruit, mycelial growth rate, minimum inhibitory concentrations(MIC), conductivity, sugar and protein content of mycelia suspension were determined, botrytis cinerea mycelial morphology by transmission electron microscopy(TEM) was found in 0.5mg/m L concentration of GBE. To find the antibacterial effect in kiwifruits with GBE, kiwifruits were immersed with different concentrations of GBE, and evaluated by physiological and biochemical indicators.The main results were as follows:1. There had five pathogens. By morphological and TTS for sequence analysis, Five pathogenic bacteria were designated as Trichothecium roseum, Fusarium tricinctum, Penicillium expansum, Colletotrichum boninense and Botrytis elliptica.2. GBE on mycelial growth of 5 kinds of plant pathogenic fungi showed different degrees of inhibition. When the concentration of GBE was 0.3mg/ml, on Trichothecium roseum growth inhibition rate reached 93.9%; against Fusarium tricinctum inhibition rate reached 98.3%; inhibition of Penicillium expansum rate of 97.7%; Colletotrichum boninense fungus mycelium growth inhibition rate reached 99.9%; mold Botrytis elliptica mycelial growth inhibition rate of 99%. GBE treatment can cause the mycelium cell membrane permeability changes, resulting in bacterial suspension sugar concentration, soluble protein content and conductivity increased, which showed GBE can damage the structure of mycelium cell membranes, leading to the increase of cell membrane permeability, cell content leakage. The TEM observation after GBE acting on the grey mold showed that the cell showed by a vacuolation and cavity.3. By grey mold infected ‘Qinmei’ Kiwifruits were immersed in GBE with four flavonoids concentration, the results showed that GBE could decrease the respiratory rate, titratable acid and hardness drop, delay soluble solids rise and botrytis cinerea lesion diameter expansion, increased the activity of peroxidase(POD), polyphenol oxidase(PPO) activity, phenylalanine ammonia enzyme(PAL), chitinase(CHT), and β-1,3-glucanase(GLU). And GBE with flavonoids concentration of 0.7 mg/m L showed the best effect.