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Kiwifruit soft rot disease is one of the main diseases after piking of which can cause enormous economic losses each year."Red Sun" kiwifruit (Actinidia chinensis Planch.var.rufopulpa Liang et Ferguson) is the main planting varieties in Sichuan, but because of "Red Sun" kiwifruit cultivation in large area and the single genetic background cause diseases and pest problems have become increasingly prominent, especially the postharvest diseases have a significant impact on the development of kiwifruit industry, the kiwifruit soft rot is one of the important diseases during storage period. This study aims to identify the soft rot bacteria of the kiwifruit from Sichuan, at the same time used ISSR molecular marker technology to research the genetic diversity of soft rot bacteria of kiwifruit from Sichuan, discussed the relationship between genetic diversity and sources of geographic, pathogenicity, and researched the physiological changes of kiwifruit after infected with pathogenic bacteria, to lay a foundation for screening of disease resistance materials.Used the conventional tissue separation to separate the pathogen of rotten kiwifruit which from kiwifruit producing areas inSichuan Dujiangyan, Shuangliu, Qionglai, Pujiang, Ya’an, Cangxi, Pengzhou. Comprehensive appraisal of morphologic and molecular biology, the results showed that kiwifruit soft rot bacteria is Botryosphaeria dothidea.Used ISSR molecular marker technology to analysis the genetic diversity of35kiwifruit soft rot bacteria strains obtained by separation. The results show that the ISSR molecular marker technique can divide the35bacteria strains into five groups, genetic distance range from0.077to0.782,as well as the average value is0.389,which means that kiwifruit soft rot bacteria in Sichuan has a highly genetic diversity. By comparison, we found that the relationship between bacteria strains geographic sources and the genetic of which is greater than the relationship between the pathogenicity and genetic distance.The activity of the SOD,POD and CAT in kiwifruit were sharply higher than control c group after kiwifruit infected soft rot bacteria. There into, the activity of SOD was2.6times of control group after2days, the activity of POD was2.2times of control group, the activity of CAT was1.4times of control group after4days. At the same time, the contents of Pro,MDA respectively increased1.2times,2.0times after3days. Results showed that the host cells removed the free radicals by increasing the activity of antioxidant enzyme as well as accumulating a lot of Pro in order to improve its permeability and adjustment ability after the pathogen infection, so as to enhancing the ability of resistance and reducing the cell damage of host cells from pathogens.
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