【作者】 高小宁；

【导师】 黄丽丽；

【作者基本信息】 西北农林科技大学 ， 植物病理学， 2006， 硕士

【摘要】 由核盘菌(Sclerotinia sclerotiorum)所致的油菜菌核病是一种世界性病害,在世界各油菜产地均造成严重危害,在我国居油菜三大病害之首。目前由于尚未发现免疫和高抗品种,所以对油菜菌核病的防治仍以化学防治为主。但大量化学药剂的使用将对人畜产生一定的毒害且造成严重的环境污染,并会导致病原菌产生抗药性。国内外已经对油菜菌核病的生物防治进行了大量研究,但有关利用植物内生细菌进行病害防治的研究报道极少。因此本试验从小麦不同生育期、不同部位分离获得的内生细菌中,筛选到1株对油菜菌核病具有较好防治效果的菌株Em7,并对其作用机理进行了初步研究。主要结果如下:1.以油菜菌核病菌为靶标菌,在PDA培养基上采用平板对峙生长法,从63株小麦内生细菌中筛选得到1株高效菌株Em7。该菌株对油菜菌核病菌的抑菌带可达到15mm,对菌丝生长有明显的抑制作用,并且能够完全抑制菌核的形成和萌发。对Em7发酵液经10 000rpm离心后得到的上清液进行试验,发现随着稀释倍数的增加,其对菌丝生长和菌核萌发的抑制作用逐渐降低。2. Em7发酵上清液对温室苗期油菜菌核病的防治效果可达95.73%。在叶片上接种病菌菌饼前后不同时间喷施发酵上清液对病害均有防治作用,但防效之间差异显著。接种前24h喷施防效为93.28%,效果最好;接种同时喷效果次之;接种后24h喷施防效为69.40%,效果最差。此外,随着发酵上清液的稀释,其防病效果逐渐降低。3.液培法测定结果表明Em7发酵上清液具有较广的抑菌谱。其对28株植物病原真菌中的22株菌丝生长的抑制效果达50%以上,并对4种病原菌孢子的萌发具有极强的抑制作用;温室盆栽结果表明,Em7对小麦条锈病、白粉病的防效也分别达到了71.36%、81.20%。4.通过光学和扫描电子显微镜观察,Em7对不同病原真菌菌丝生长发育的影响不同,主要分为以下几类:(1)细胞质外渗;(2)菌丝畸形;(3)菌丝丛生;(4)顶端膨大等。Em7发酵上清液经硫酸铵沉淀,透析去盐后的溶液对菌丝生长具有明显抑制作用,初步认为其抑菌活性可能是抗菌蛋白或多肽的作用。此外,Em7菌悬液对萝卜、白菜种子萌发及生长具有一定的促进作用。5. Em7无菌上清液对高温具有一定的忍耐程度,100℃处理30min后,其抑菌作用与未处理的之间无显著差异,且在碱性条件下较稳定。经过筛选,Em7在以下条件培养,更多还原

【Abstract】 The Sclerotinia sclerotiorum of oilseed rape is one of the major diseases of oilseedrape in the world. It is much severe in China. Biological control of sclerotinia disease, as an important alternative to chemical control, has received considerable attention due to the lack of resistant varieties, and increasing concerns over fungicide resistance in populations of S. sclerotiorum and fungicide residues in the environment. In recent years, fungal biocontrol agents were largely studed for the biocontrol of sclerotinia disease of oilseed rape. However, the report that this disease was controlled with endophytic bacteria is few. So, effects of endophytic bacteria isolated from winter wheat on S. sclerotiorum were studied in this thesis.The main results were as follows:1. Through dural culture assay, endophytic bacterium Em7 isolate was screened out from 63 isolates on PDA medium, which should strongly inhibit the growth of S. sclerotiorum. It also should inhibit the formation of sclerotia and the germination of sclerotia. The results showed the inhibitory rate dereased with the increasing of times of dilution of Em7 filtrate by the means of the liquid culture.2. In greenhouse experiments, the filtrate of Em7 isolate had 95.73% control effect against S. sclerotiorum. The biocontrol efficacies were different by spaying filtrate of Em7 in different time. Before 24h of inoculation S. sclerotiorum, the biocontrol efficacy was highest 93.28%; it was lowest by spaying Em7 filtrate after 24h of inoculation S. sclerotiorum. Different times of dilution of filtration had different effects on the biocontrol efficacy. With the increasing of times of dilution of Em7 filtrate, the biocontrol efficacies decreased.3. Antagonistic bacterium Em7 isolate had the broad-spectrum inhibitory effect to plant pathogens. By the means of the liquid culture, the results indicated that cell free filtrate of Em7 isolate had more than 50% inhibition rate against 22 pathogens. It should also strongly inhibit the germination of spores of 4 pathogens. The Em7 filtrate had 81.20% and 71.36% control effect against Blumeria graminis f.sp. tritici and Puccinia striiformis f.sp. tritici in glasshouse trials.4. Antagonistic bacterium Em7 isolate induced diverse morphological alterations in更多还原