Studies On Preharvest Regularity Of Infection And Molecular Detection Of Banana Anthracnose

The pathogen of banana fruit anthracnose was isolated from 30~70 days banana fruit using organic separation method. The isolated pathogen included hypovirulent strains Z1, Z2 and high virulent strains Z3, Z4. The cultural characteristics between hypovirulent strain and high virulent strain was highly distinct.The pathogen of banana anthracnose latents on fruit, foliage, bract, blossom and stalk, stalk of plants with this disease is the most important carrier. The infection type of bannana fruit anthracnose is latent infection. The fruit of banana became carrier after 20 days of blossom, and the quantity of the pathogen increased gradually with the time prolong. After that the quantity of the pathogen of each growth phases related to rain fall. The the quantity of the pathogen of different parts was 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.The development process of conidia of Colletotrichum musae on fruit was not distinct from foliage and stalk.Two pairs of PCR primers were designed according to the two especial fragment (357bp and 206bp) of Colletotrichum musae. Banana tissue culture seedling genomic DNA, banana anthracnose pathogen genomic 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. Take the above genomic DNA as model, results from assays done with one pairs of primers showed that 357bp fragment was amplified from genomic DNA of C. musae while others not.So the pair of primers 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.