Banana Fruit Anthracnose Pathogenesis,Pathological Physiology And Biochemistry And Cloning Of Pathogenesis-related CDNA Fragments

Postharvest decay of fruits and vegetables is an urgent problem in the world. 25% economic loss is produced because of postharvest decay of fruits and vegetables every year in the world. Deterioration of fresh fruits and vegetables is influnced by many factors but postharvest diseases caused by fu'ngi and bacteria are main factor. 10%~30% yield of fresh fruits and vegetables is lost because of postharvest decay in developed countries, 40%~50% yield of fresh fruits and vegetables is lost becaused of shortage of cold-storage installation in developing countries. Econocic loss of bnana fruit postharvest decay is about 15%~30% because of shortage of effective antiseptic measures and equipment.Banana fruit anthracnose is a typical postharvest disease. The study of pathogenesis, molecular detection, pathogenesis-related genes cloning plays a crucial role in controlling banana fruit anthracnose and conducting gene-engineering resistance breeding. In the meantime, this study sets an example for other fruits and vegetables postharvest diseases research.This study began with isolating the pathogen of banana fruit anthracnose. The pathogen was isolated from 30-70 days banana fruit. The isolated pathogen included hypo virulent strains Z1, Z2 and high virulent strains Z3, 74. The cultural characteristics between hypovirulent strain and high virulent strain was highly distinct.Infection process of banana fruit anthracnose pathogen was observed using free-hand section and paraffin section. Banana fruit were inoculated by conidia suspension, conidia germinated within 6hr, produced dilutus appressoria within 12hr,produced dematiaceous appressoria within 24hr. Appressoria were latent in intercellular cleft and were latent until banana fruit were harvested.Banana tissue culture seedling genomic DNA, banana anthracnose pathogengenomic DNA, mango anthracnose pathogen genomic DNA, rubber anthracnose pathogen genomic DNA, watermelon anthracnose pathogen genomic DNA, banana crown rot pathogen genomic DNA, stylo anthracnose pathogen genomic DNA, watermelon Fusarium wilt pathogen genomic DNA were extracted using SDS method. Specific fragment was produced using random primer MQ8185 and was cloned, sequenced. The sequence of specific fragment was new in the Genbank.Dot hybridization indicated that there was hybridization signal in ail three templates. 357bp probe was designed according to BLASTn analytical result and was used to Southern hybridization. The result was that 357bp fragment was endemic in banana anthracnose pathogen genomic DNA. So the 357bp fragment could be used to molecular detection of banana anthracnose.There was interference phenomena between banana template and its pathogen template. The target fragment couldn't produce when banana template doubled its pathogen template. The target fragment produced when the above mixed templates were treated by enzyme hydrolysis(EcoR I ). The target fragment couldn't produce when EcoR I was exchanged for Pst Hind.The target fragment produced when banana fruit were inoculated by high concentration conidia suspension, the target fragment couldn't produce when banana fruit were inoculated by low concentration conidia suspension.Endochitinase activity and exochitinase activity were assayed according to Boiler's method after banana fruit were harvested. Endochitinase activity and exochitinase activity were gradually elevated every day not only the inoculated banana fruit but also the non-inoculated banana fruit, the fifth day activity was maximum.Pathogcnesis-related up-regulated genes and pathogenesis-related down-regulated genes were cloned combining Suppression Subtractive Hybridization(SSH) and microarray technology.