Isolation and identification of endophytic Bacillus cereus B4-2 against pumpkin powdery mildew and effect of biological control
In order to find the new biological control method against pumpkin powdery mildew,this experiment screened the endophytic antagonistic bacteria against pumpkin powdery mildew from high resistance plants.The spore germination inhibition method,leaf disk floating method and greenhouse pot experiment method were used to select endophytic bacteria with good control effect,which was identified by morphological observation,physiological and biochemical determina-tion as well as molecular biology method.The results showed that 29 endophytic antagonistic bacterial strains were isolated from the high resistant pumpkin inbred line 22G3.Among them,5 strains had an inhibition rate of over 50%on the spore germination of powdery mildew,and B4-2 had the highest inhibition rate of 88.65%.Both leaf disc and potting experi-ments showed that the strain B4-2 had the best control effect on pumpkin powdery mildew,with the control effects of 79.58%and 83.21%,respectively.All the different dilution ratios of B4-2 fermentation had certain control effects on pumpkin powdery mildew.As the dilution ratio increased,the prevention effect decreased.The prevention effect of original B4-2 solution was the best and was 82.14%.B4-2 was identified as Bacillus cereus by morphological,physiological,bio-chemical and gene sequence analysis methods.In summary,B.cereus B4-2 can effectively control pumpkin powdery mil-dew,which has certain potential for development.