Analysis On The Adnascent Microorganism Flora Of Grape Leaves And Screening Of Antagonistic Strain To Botrytis Cinerea

Grape grey mold, one of the most major grape diseases, contributes to the great loss of grape production all over the world. While agronomic and chemical approaches are majorly applied to control this disease, both of these two methods have limitations.In the present study, we analyzed the profile of adnascent microorganism flora on grape leaves, antagonistic strains screening and identification, and preventive effects of isolated bacteria at different conditions in Tianzhu greenhouse and Honggu natural farm. The results are detailed as follows:1 The profile of adnascent microorganism flora of grape leavesWe compared the epiphytic microorganism flora on the grape leaves using serious dilution plate culture at different grape growth stages including young fruit enlargement, pigmentation and maturity in Tianzhu greenhouse and Honggu natural farm. The results showed that the amount and strains of fungi and bacteria from Honggu are remarkable more than that from Tianzhu. In Honggu natural farm, epiphytic microorganism gradually increased from the enlargement stage to the maturity stage and then decreased, and the number of epiphytic microorganism is much more than that of filamentous fungi or yeasts; In Tianzhu greenhouse, however, the filamentous fungi increased quickly from enlargement stage and up to maximum at pigmentation stage, and then decreased at maturity. Yeasts were found only at pigmentation and maturity. Moreover, the amount of filamentous fungi is much higher than the amount of bacteria in maturity in Tianzhu.2 Screening of antagonistic strainWe selected 28 strains of bacteria inhibiting grape grey mold from bacteria collected from grape leaves using plate screening. We further confirmed 21 strain anti-grap grey mold bacteria from the 28 strains using confront experiments, and finally selected 10 strains for further studies.The results germination inhibition and mycelium growth tests showed that strains BHG13 and BTZ7 are the strongest bacteria in inhibiting growth of grape grey mold, and BTZ5 and BHG7 are the weakest bacteria in grape grey mold inhibition. In vitro study demonstrated that the preventive effect in inhibiting fungi by these bacteria is much better than the therapeutic effect.3 Identification of BHG13 and BTZ7 strains After comparing the size, color of the clone, observation of microscope with Gram's stain and PCR of 16SrDNA, we concluded that both BHG13 and BTZ7 are Pseudomonas sp.4 Prevention effects of BHG13 and BTZ7 strains on grape gray moldBoth BHG13 and BTZ7 strains can grow on grape leaves, and the setting period is from 15 d to17 d. The prevention test in greenhouse showed that the prevention efficiency of both BHG13 and BTZ7 strains in nature is above 50%.