Isolation and Characterization of Endophytic Bacteria for Phytophthora sojae Inhibition from Soybean Plant

Phytophthora sojae is a worldwide destructive pathogen to soybean.To isolatate endophytic bacteria from soybean is an important idea in dealing with the deseases caused by P.sojae.In this study,67 endophytic bacterial strains were isolated from soybean root,of which 18 strains showed obvious inhibition ability on the mycelia of P.sojae.Especially,the strains A2,A4,A7 and B8 showed an even strong inhibition effect,with the inhibition rates being 72.8%,55.5%,76.0% and 87.1%,respectively.The sterile fermentation filtrate of A2 and A4 inhibited germination rates of P.sojae spores by 75.4% and 85.8% in a plate test.These two endophytes also promoted the germination rates of pathogen-infected soybean seeds from 63.1% to 80.0% and 80.3%,of which the seedlings showing a healthy growth state increased from 31.4% to 45.7% and 50.9%,respectively.Based on 16S rDNA sequence phylogenetic analysis,A2 was identified as Pseudomonas sp.and A4,A7,B8 as Bacillus spp.