A comparison of DNA base compositions among anastomosis groups in Rhizoctonia solani Kuehn.

Abstract

Base composition of DNAs of 30 isolates of Rhizoctonia solani Kuhn was compared. The relationships between the base composition of DNA and each anastomosis group or cultural type were investigated. The range of guanine plus cytosine (GC) content of R. solani DNA was 40.9 to 49.3 mole%, and its average was 45.3 mole%. The GC contents of the isolates within each anastomosis group were almost same. Little difference of GC content was observed between the sasakii type (IA) and the web-blight type (IB) in AG-1. Furthermore GC contents of the rush type (IIIB) and the root rot type (IV) in AG-2-2, were quite similar. While a significant difference was observed between the potato type (IV) in AG-3 and the root rot type (IV). AG-1 showed the highest GC content (avg. 48.8 mole%) among all of the anastomosis groups, followed by AG-4 (avg. 47.3 mole%), AG-3 (avg. 47.1 mole%), AG-5 (avg. 45.2mole%), AG-2-2 (avg. 44.6 mole%), AG-2-1 (avg. 43.7 mole%), AG-6 (avg. 41.8 mole%) and AG-BI (avg. 41.4 mole%). These results suggest that each anastomosis group must be regarded as a genetically independent unit.