拮抗大豆疫霉菌植物内生细菌的筛选与鉴定

大豆疫霉根腐病是世界范围内危害严重的毁灭性大豆病害,筛选内生菌进行生物防治是未来该病害防治的重要发展方向。以大豆根系为材料筛选得到67株内生细菌,采用平板对峙生长实验,发现其中18株对大豆疫霉菌的菌丝生长具有抑制作用,其中以A2、A4、A7和B8效果最佳,抑制率分别达到72.8%、55.5%、76.0%和87.1%。利用无菌发酵滤液与大豆疫霉孢子共培养发现,A2和A4对孢子萌发具有明显抑制效果,抑制率达75.4%和85.8%。盆栽实验表明,A2和A4无菌发酵滤液能使经大豆疫霉孢子侵染后的大豆种子萌发率由63.1%分别提高到80.0%和80.3%,健康幼苗率由31.4%提高到45.7%和50.9%。根据16S rDNA序列系统发育分析,初步确定A2为假单胞菌(Pseudomonas sp.),A4、A7和B8皆为芽孢杆菌(Bacillus sp.)。

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.