论文部分内容阅读
从类似纹枯病的水稻病株上分离到一种在菌核形态上与纹枯病菌(Rhizoctonia solani)有明显差异的真菌,致病性测定结果表明该菌能侵染水稻、玉米和大豆。对该菌的显微形态、生物学特性以及核糖体DNA-ITS序列进行研究,结果表明该菌为嗜水小核菌(Sclerotium hydrophilum Sacc.)。病菌在30℃、pH为6~9条件下生长表现最佳,属硫胺素自养型菌;营养菌丝与立枯丝核菌相似,菌核球形或椭圆形,数量极多,其平均大小仅为386.4μm×420.7μm;该菌的核糖体DNA-ITS序列与GenBank中唯一一个嗜水小核菌(登录号为DQ875597)的同源性为99.5%,并且与大多数丝核菌(Rhizoctonia spp.)也有一定的同源性,病菌的28S rDNA-RFLP分析结果进一步说明了该菌在系统发育上与丝核菌类真菌具有较高的同源性。通过比较该菌和几种与水稻纹枯病相关丝核菌核糖体DNA-ITS序列的差异,设计了一对特异性引物PS-1和PS-2,能专一地从被该菌侵染的水稻感病组织中扩增出一段约550bp的DNA。
A fungus with obvious difference in sclerotial morphology from Rhizoctonia solani was isolated from a blight-like rice diseased plant. The pathogenicity test showed that the fungus could infect rice, corn and soybean . The microscopic morphology, biological characteristics of the bacteria and ribosomal DNA-ITS sequences were studied, the results show that the bacteria is Sclerotium hydrophilum Sacc. The bacteria grew best under the conditions of 30 ℃ and pH 6 ~ 9, and was a thiamine autotrophic fungus. The vegetative mycelium was similar to Rhizoctonia solani, the number of which was very large, The size of which was only 386.4 μm × 420.7 μm. The homology of the ribosomal DNA-ITS sequence of this strain with the only one in GenBank (Accession No. DQ875597) was 99.5% and was identical to that of most Rhizoctonia solani Rhizoctonia spp.). The 28S rDNA-RFLP analysis of the bacteria further demonstrated that the strain has high homology with Rhizoctonia fungi in phylogeny. A pair of specific primers, PS-1 and PS-2, were designed to compare the difference between this strain and several DNA-ITS sequences of R. solani associated with rice sheath blight. Of rice susceptible tissue amplified a period of about 550bp of DNA.