Screening and identification of antagonistic strains of soybean Botrytis cinerea and Alternaria tenuissima

Bio-control for inhibiting pests and diseases is one of the important approaches for sustainable agricultural development.Botrytis cinerea and alternaria tenuissima are two main soybean diseases.In order to better control Botrytis cinerea and Alternaria tenuissima,we isolated 64 strains of antagonistic bacteria from the rhizosphere soil of wild rice in Jiangxi Province by soil dilution method.The results showed that A2,A6,A10,F7 and G6 strains were with stable antagonism against Botrytis cinerea and Alternaria tenuissima by repeated screening and plate confrontation assay.The inhibition rate of the antagonistic fermentation filtrate was much higher than that of the chemical pesticide.The optimal inhibition rate of the antagonistic fermentation filtrate against Botrytis cinerea and Alternaria tenuissima was 91.7% and 60.9%-87.0%,respectively; while that of the chemical pesticides was only 68.0% and 47.3%,respectively.By analysis of strain physiological and biochemical characteristics as well as the identification of 16S rDNA,we determined that five strains were Streptomyces misionensis,Micromonospora purpureochromogenes,Streptomyces ansochromogenes,Streptomyces species,and Panenibacillus species.This study would provide technical support for the development and utilization of bio-control bacteria in controlling soybean Botrytis cinerea and Alternaria tenuissima.