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为筛选一种对小菜蛾有高致病力的杀虫真菌,对来自不同地域的环链棒束孢菌株的培养特征尤其是孢梗束形成、对小菜蛾的致病性和基于5.8S-ITS nrDNA构建的系统发育等进行分析。结果表明,供试菌株的培养性状可分为3个类型:孢梗束浓密型、孢梗束稀疏型和不产孢梗束型。孢梗束浓密型对小菜蛾的致病性最高,平均达到88.9%,其中XS.1菌株,对小菜蛾幼虫的致死率达到98%;孢梗束稀疏型次之,为68.4%;不产孢梗束型最差,仅35%。系统发育聚类树分析表明,在环链棒束孢菌株中,致病性较高的菌株,如XS.1,XS.2和SL.7等聚在一亚分支内,致病性低的菌株8.02和468.10聚在一起;不产孢梗束的两个菌株8.02和468.10聚在一个亚支。这些结果表明环链棒束孢菌株间具有明显的种内遗传变异性。孢梗束形成与小菜蛾的致病死亡率有相关性。孢梗束的形成可作为高致病性菌株选择的一个重要指标。
To screen for a highly pathogenic insecticidal fungus to Plutella xylostella, the culture characteristics of different strains of Corynebacterium isolates from different regions, especially the formation of sporulation, the pathogenicity to Plutella xylostella, ITS nrDNA constructed phylogenetic analysis. The results showed that the culture traits of the tested strains could be divided into three types: spore bundle dense type, spore bundle sparse type and non-sporulation stem bundle type. The density of spore-bundle dense was the highest on the diamondback moth, with an average of 88.9%. The lethal rate of XS.1 to the diamondback moth larvae reached 98%, followed by sparse spores of 68% The worst type of spore and stem was only 35%. Phylogenetic tree analysis showed that among the strains of Corynebacterium parvum, the most pathogenic strains, such as XS.1, XS.2 and SL.7, clustered in a sub-branch with low pathogenicity Strain 8.02 and 468.10 were clustered together; two strains 8.02 and 468.10 of non-sporulating stem gathered in one sub branch. These results indicate that there is a significant intraspecific genetic variability among the strains. There was a correlation between the formation of sporulation and pathogenic mortality of diamondback moth. The formation of spore bundles can be used as an important indicator of the selection of highly pathogenic strains.