College of Life and Environmental Sciences, Shanghai Normal University, Shanghai 200234, P. R. China.
J Microbiol. 2011 Dec;49(6):884-9. doi: 10.1007/s12275-011-1261-4. Epub 2011 Dec 28.
Sclerotinia stem rot (SSR) caused by the fungus Sclerotinia sclerotiorum has been an increasing threat to oilseed rape (Brassica napus L.) cultivation. Efficient and environment-friendly treatments are much needed. Here we focus on microbial control. The Pseudomonas fluorescens P13 that was isolated from oilseed rape cultivation soil, proved to be a useful biocontrol strain for application. Morphology, physiological and biochemical tests and 16S rDNA analysis demonstrated that it was P. fluorescens P13 and that it had a broad antagonistic spectrum, significantly lessening the mycelial growth of S. sclerotiorum by 84.4% and suppressing sclerotial formation by 95-100%. Scanning electron microscopy studies attested that P13 deformed S. sclerotiorum mycelia when they were cultured together. P13 did not produce chitinase but did produce hydrogen cyanide (HCN) which was likely one of the antagonistic mechanisms. The density of P13 remained at a high level (≥10(6) CFU/ml) during 5 weeks in the rhizosphere soil and roots. P13 reduced SSR severity at least by 59% in field studies and also promoted seedling growth (p<0.05) at the seedling stage. From these data, our work provided evidence that P13 could be a good alternative biological resource for biocontrol of S. sclerotiorum.
菌核病（SSR）是由核盘菌引起的，对油菜（甘蓝型油菜）种植构成了日益严重的威胁。迫切需要高效和环保的处理方法。在这里，我们专注于微生物控制。从油菜种植土壤中分离出的荧光假单胞菌 P13 被证明是一种有用的生物防治菌株。形态学、生理生化试验和 16S rDNA 分析表明，它是荧光假单胞菌 P13，具有广泛的拮抗谱，对核盘菌的菌丝生长抑制率达 84.4%，对菌核形成的抑制率达 95-100%。扫描电子显微镜研究证明，P13 与核盘菌共培养时会使核盘菌菌丝变形。P13 不产生几丁质酶，但产生氰化氢（HCN），这可能是其拮抗机制之一。在根际土壤和根系中，P13 的密度在 5 周内保持在较高水平（≥10(6) CFU/ml）。在田间研究中，P13 至少将 SSR 严重程度降低了 59%，同时在幼苗期也促进了幼苗生长（p<0.05）。从这些数据可以看出，P13 可以作为防治核盘菌的一种良好的生物防治替代资源。
