RFLP analysis of the PCR-amplified 28S rDNA in Rhizoctonia solani

RFLP analyses of a portion of the 28S rDNA gene region were conducted by using four restriction endonucleases for 57 isolates of 13 intraspacific groups (ISGs) representing 7 anastomosis groups (AGs) of Rhizoctonia solani. Variations in the PCR-amplified rDNA products and the polymorphisms on digestion with restriction enzymes (BamHI, Haelll, Hhal and Hpall) were observed among three AGs, AG 1,2 and 4. These differences were also conserved among some ISGs of AG 1 and AG 2. Among ISGs of AG 1, the pattern of rDNA fragments of AG 1-1A obtained by digestion with Hpall was significantly different from those of AG 1-1B and IC. Such difference in the fragment pattern was also observed among AG 2-1, 2-2 IIIB and 2-2 IV by the digestion with Hhal and Hpall. A dendrogram derived from the restriction enzyme data showed that ISGs from AG 1 and AG 2 can each be subdivided into distinct groups, those are distantly related to the majority isolates of the other AGs.