中国北方棉花主产区立枯丝核菌的融合群鉴定

从山东、河北、河南三省采集棉花立枯病样品和土壤200余份，经分离获得198个丝核菌Rhizoctonia solani分离物。菌丝融合测定及5.8S rDNA-ITS区序列分析结果表明，这些分离物分别属于多核丝核菌的AG4-HG-I和AG4-HG-III融合群以及双核丝核菌的AG-A、AG-F、AG-Fb融合群。其中AG4-HG-I是优势融合类群，占分离物总数的88.38%，其次是AG4-HG-III，占10.10%，AG-A、AG-F、AG-Fb各仅有1株。其中双核丝核菌AG-A、AG-F和AG-Fb融

Anastomosis groups of Rhizoctonia solani from cotton in northern China

A total of 198 Rhizoctonia solani isolates were obtained from diseased cotton and soil samples in northern China(Shandong,Hebei and Henan provinces).Anastomosis group(AG) assay and 5.8S rDNA-internal transcribed spacer(ITS) sequence analysis showed the presence of multinucleate Rhizoctonia AG4-HG-I,AG4-HG-III and binucleate Rhizoctonia AG-A,AG-F and AG-Fb groups.The group AG4-HG-I was the dominant(86.86% of total isolates),followed by AG4-HG-III(10.10%),while the AG-A,AG-F,AG-Fb groups were represented by single isolate respectively.The Rhizoctonia AG-A,AG-F,AG-Fb groups were firstly reported from diseased cotton plants,and their pathogenicity to cotton needs further investigation.The 5.8S rDNA-ITS sequence analysis showed that the isolates could be distinctly separated based on their AG types.The isolates of the same AG(or sub-AG) showed high sequence identity.The nuclear phase observation showed that the numbers of nuclei were significantly different between the two subgroups of AG-4.