The present study obtained 12 isolates from Rhizoctonia solani Kühn isolated from Cotton L., Trifolium L. and Vicia faba L. from different localities in the Nile Delta of Egypt. All strains were pathogenic and caused seed rot, wilt, stunting, and preemergence and post-emergence damping-off. | Turk J Bot 31 (2007) 19-29 © TÜB‹TAK Research Article Genetic Diversity among Nile Delta Isolates of Rhizoctonia solani Kühn Based on Pathogenicity, Compatibility, Isozyme Analysis and Total Protein Pattern Yehia . MAHMOUD*, Reda M. GAAFAR, H. M. MUBARAK Botany Department, Faculty of Science, Tanta University, Tanta 31527, EGYPT Received: Accepted: Abstract: The present study obtained 12 isolates from Rhizoctonia solani Kühn isolated from Cotton L., Trifolium L. and Vicia faba L. from different localities in the Nile Delta of Egypt. All strains were pathogenic and caused seed rot, wilt, stunting, and preemergence and post-emergence damping-off. The isolated strains produced different forms of infection cushions that ensure the pathogenicity of these strains. SDS-PAGE of the 12 R. solani isolates showed that although the R. solani isolates were isolated from very divergent host plants, the total soluble protein patterns among them were similar. Isozyme analysis revealed higher polymorphism among R. solani isolates using the EST isozyme. The cluster analysis based on isozyme data showed that the R. solani isolates fell into 4 distinct groups, whereas the dendrogram resulting from cluster analysis based on the compatibility test and other morphological characteristics of pathogen infection cushion showed that all R. solani isolates were placed into 3 main distinct groups. Key Words: Genetic diversity, Rhizoctonia solani, SDS-PAGE, isozymes, anastomoses Introduction Rhizoctonia solani Kühn pathogenicity is complex; it has heterogeneous strains and diversity in host range. It occurs throughout the world and can damage any part or all of a plant. It is known to cause seed decay, dampingoff, seedling blight, root rot and crown rot, as well as soreshin and wirestem, hypocotyls cankers, bud rot, foliage blight and storage rots (Mubarak, 2003). R. solani generally attacks seedlings at the ground level (hypocotyls) and grows downwards into the
