黄瓜菊苣假单胞菌叶斑病内生拮抗细菌的鉴定及促生作用

从湖南、云南、海南等地采集的健康黄瓜植株中分离得到189株内生细菌,从中筛选的内生细菌Y–10对黄瓜叶斑病病原菌菊苣假单胞菌(Pseudonwnas cichorii)的抑菌半径达16 mm,拮抗效果最好,经形态学、生理生化特性及16S rDNA和rpoA双基因联合建树分析,被鉴定为枯草芽孢杆菌(Bacillus substilis).分别用4×109、4×108、4×107、4×106、4×105 cfu/mL的Y–10菌液浸黄瓜种子和4×109、4×108、4×107、2×107、4×106 cfu/mL的菌液灌根处理黄瓜盆栽幼苗,以无菌水浸种和灌根处理作为空白对照.结果显示,Y–10菌液4×107 cfu/mL处理的种子发芽率较空白对照提高了6.01％,菌液4×109 cfu/mL处理的种子几乎不萌发;黄瓜幼苗的根长、根鲜质量、地上部鲜质量、地上部干质量分别提高了40.71％、33.59％、35.21％、58.18％.4×109 cfu/mL菌液灌根接种后,黄瓜幼苗根长、根鲜质量、地上部的鲜质量和干质量分别较空白对照提高了11.49％、19.57％、77.25％、47.15％.Y–10菌株无溶磷、解钾及产IAA作用,但具固氮、产铁载体的作用.

Isolation and screening of endophytic antagonistic bacteria against cucumber leaf spot Pseudomonas cichorium and its growth promotion effect

One hundred and eighty-nine endophytic bacteria strains were isolated from healthy cucumber plants collected from Hunan, Yunnan and Hainan. The inhibitory radius of strain Y-10 to Pseudomonas cichorium, the pathogen of cucumber leaf spot, was 16 mm, and the antagonistic effect was the best. The strain Y-10 was identified as Bacillus subtilis by combining the results of morphological, physiological and biochemical characteristics and 16S rDNA and rpoA genes analysis. Bacterial suspensions of strain Y-10 was diluted to 4×109, 4×108, 4×107, 2×107, 4×106, 4×105 cfu/mL by gradient dilution, and 4×108, 4×107, 4×106, 4×105 cfu/mL suspensions were selected to soak seeds separately, while 4×109, 4×108, 4×107, 2×107, 4×106 cfu/mL solutions were used to irrigate seedlings independently. Sterile water soaking and root irrigation were used as blank controls. The results show that some dilutions of strain Y-10 could promote the cucumis seedling growth and seeds germination. After soaking seeds with 4×107 cfu/mL bacterial solution, the germination rate of seeds was 6.01% higher than that of the blank control. The seeds hardly germinated when treated with 4 ×109cfu / mL bacterial solution, and the root length, root fresh weight, shoot fresh weight and shoot dry weight of cucumber seedlings increased by 40.71%, 33.59%, 35.21% and 58.18% respectively. In the treatment with 4 ×109cfu / mL bacterial solution irrigation, the root length, root fresh weight, shoot fresh weight and shoot dry weight of cucumber seedlings, compared with the blank control, were increased by 11.49%, 19.57%, 77.25% and 47.15%, respectively. Strain Y-10 had no function of dissolving phosphorus and potassium and producing IAA, but had the function of fixing nitrogen and producing iron carrier.