THE USE OF PROTOPLASTS FOR THE PREPARATION OF HOMOKARYONS FROM HETEROKARYOTIC ISOLATES OF RHIZOCTONIA-SOLANI

A technique for preparing homokaryotic strains from heterokaryotic isolates of Rhizoctonia solani is described. Protoplasts were released from the heterokaryotic mycelium and mononucleate protoplasts were concentrated by low-speed centrifugation. The protoplasts were regenerated and homokaryons were selected on the basis of their ability to form a heterokaryon with known homokaryotic single-basidiospore isolates. The homokaryotic nature of these isolates was confirmed by pairing them with each other in all possible combinations. The method was used to prepare homokaryons from a dikaryon synthesized from two homokaryotic single-basidiospore isolates and from a heterokaryotic field isolate. This technique should prove to be useful for preparing homokaryons from isolates of R. solani which cannot be induced to sporulate.