Selection And Identification Of Dominant Antagonistic Yeasts Of Banana Anthracnose

Banana, an important tropical fruit, has the biggest world trade volume in tropical fruit commodity. Banana is a type of respiration climacteric fruit. In the ripening process, it is susceptible to pathogens and disease, which can cause a large number of fruit rot and result in serious economic losses. Banana anthracnose is one of the main postharvest diseases. Postharvest biological prevention study of banana can effectively control the incidence of postharvest diseases, extend the storage period, improve the rate of good fruit, ensure fruit health and safety, and reduce economic losses.In this study, the yeasts were separated from eight different varieties of bananas and then purificated. Advantage antagonistic yeasts were screened out by in vitro screening and in vivo screening, which can significantly inhibit on banana anthracnose. Then the advantages antagonistic yeast strains were identified by morphological characters, physiological and biochemical indexes, molecular biological method. Experiment results were as follows.1.329 yeast strains were purified from the health banana peel surface and the banana junction of healthy area and anthrax disease area of 8 different varieties, including 8818 banana, red banana, fen banana, plantain, Brazil banana, emperor banana, Thai banana and zhima banana.2. Some bacteria were isolated from the typical banana anthracnose fruits, using rDNA-ITS sequence analysis for the pathogen identification, we could find that the length of rDNA-ITS sequences is 575 bp, and it is 99% homology compared with Colletotrichum musae. Combining with the experiment results and the biological characteristics of pathogenic bacteria, we could conclude that the pathogen isolated is the Colletotrichum musae.3. Three yeast strains, named Z-BR-16、Z-BP-④4 and Z-BP-①Ⅰ2, which had obvious antagonism effect on anthrax pathogen, were chosen from the 329 in vitro screened yeast strains. The radius of their inhibition zones were respectively 0.475 cm,0.463 cm and 0.363 cm.4. Using the three yeast strains having the most obvious antagonism anthrax pathogen to banana anthracnose anthrax which screened from the in vitro screening for in vivo screenings, screening out the best and the most antagonistic effect and dominant stable antagonistic yeast strain Z-BR-16, with sterile water as control,7 days after inoculation, the highest inhibition rate of the 1.0×108 CFU/ml bacilli to banana anthracnose is 75.94%.5. Through morphological characters, physiological and biochemical indexes, the results showed that the main features of the yeast are round or oval cells, multilateral budding, usually with pseudohyphal, little even no mycelium,1 to 4 hat-shaped or saturn-shaped spores in each ascus, release of the spores when mature due to the easily broken ascus, fermentation of glucose, and dissimilation of nitrate, the searching result showed that the Z-BR-16 yeast is Pichia anomala. Through the rDNA-ITS sequence analysis, we could draw that the length of the r DNA-ITS sequence of the yeast is 617 bp and the max ident is 100% compared with the sequence of the Pichia anomala. Combining with the 3 aspects identification results of morphological characters, physiological and biochemical indexes, the rDNA-ITS sequence analysis, we concluded that the advantage antagonistic yeast strain Z-BR-16 is Pichia anomala.