Variation in pathogenicity and cultural characteristics among isolates reverted from protoplasts of Sclerotium rolfsii

Abstract

Protoplasts were isolated from the parent isolate (SR8501) of Sclerotium rolfsii by a previously reported combination of enzymatic methods using Cellulase Y-C (1%), Driselase (1%), Zymolyase-20T (0.1%), Chitinase (0.1%) and Pectolyase Y-23 (0.1%). Most of the protoplasts had a single nucleus. A single protoplast suspended in a small drop of potato broth containing 0.6M sucrose as an osmotic stabilizer was able to regenerate its cell wall and revert to mycelium with a relatively high frequency. Virulence on soybean susceptible to the parent isolate, pathogenicity to some other crops, and cultural characteristics were altered in many of the revetant isolates, compared with the parent isolate. These characteristics of the revertant isolates were stable in their frequent transfer to new media. This variability may essentially reflect the genetic potential of the parent isolate, although a mutation might be involved in some of the new characters.