To evaluate the role of the RS-toxin, a phytotoxin produced by the fungus Rhizoctonia solani that causes sheath blight disease of rice, varying doses of gamma irradiation were used to generate mutants of the fungus. All the mutants showed reduced mycelial growth compared to the wild isolate RS7 in liquid culture. The mutants exhibited significant differences in virulence on detached leaf sheath and intact rice plants, the toxin produced and sclerotial formation in culture media and infected leafsheaths. The amount of toxin produced was positively correlated with disease development. SDS-PAGE analysis of mycelial proteins showed that the mutants and wild isolate produced many proteins of different molecular weights at different stages of mycelial growth. In the mutants resulting from higherdoses of gamma rays, the amount of toxin produced and their ability to induce disease symptoms were also greatly reduced.
Babu S., Nandakumar R., Sriram S., Raguchander T., Balasubramanian P., Samiyappan R. (2003): Phytotoxin production and rice sheath blight development by Rhizoctonia solani mutants derived from gamma irradiation. – Czech Mycology 55(3-4): 261–271.
