Assessment of Characteristics for Determining Pathogen Populations of Rhizoctonia Solani in Rice-Based Cropping Systems

Abstract

Rhizoctonia solani is the causal agent of rice sheath blight, a major constraint to rice production in many SE Asian countries. R. solani is considered to be a ‘collective species’ and genetic diversity within the species is represented by anastomosis groups (AGs) defined from hyphal anastomosis behaviour. Within the AGs other intraspecific groups (ISGs) have been defined on the basis of morphology, pathology, pectinase isoenzymes and DNA sequence homology (Vilgalys & Cubeta, 1994). Isolates of R. solani in tropical rice-based cropping systems are generally found to belong to AG-1 1A, but there is little information about diversity among these isolates. Such information is of vital importance for resistance breeding and the development of strategies for disease management.