DNA-PROBE SPECIFIC TO RHIZOCTONIA-SOLANI ANASTOMOSIS GROUP-8

A DNA probe was developed which hybridizes strongly with DNAs of all i solates of Rhizoctonia solani anastomosis group 8 (AG-8) tested. The p robe hybridized only weakly or not at all with DNA of isolates from ot her anastomosis groups. The results presented here indicate that the p robe recognizes a dispersed repeated DNA element in AG-8 isolates and that genetic variation occurs within AG-8. Preliminary experiments sho w that the repeated unit is at least 1.8 kbp in length and that sequen ce variation occurs between different repeat units. The probe has the potential to further our understanding of the population dynamics of b are patch disease in cereal crops.