An Experimental Study on Mutation Induction Technique of Pythium guiyangense Su, A Fungal Pathogen of Mosquitoes
［Key words］ Pythium guiyangense Su; protoplasts; ultraviolet rays; lithium chloride; mutation breeding
To establish a mutation induction system for mutation breeding of Pythium guiyangense Su, a fungal pathogen of mosquitoes. Methods: Protoplasts of original strain were treated with UV or LiCl for mutation induction. Casein plate transparent loop method and mycelial weight determine were used to screen mutant colonies. Pertinent induction condition combination were summarized based on the analysis of the relationship between the positive mutation rates and treatment dosages and periods of UV or LiCl. One of the mutational colonies was continuously cultivated for 8 generations on KPYG2 plates for the observation of genetic stability. Results: A lethal rate of 86.9% and a positive mutation rate of 26.9% were achieved when the protoplasts were treated by 0.6% of LiCl for 90mins, and a lethal rate of 81.3% and a positive mutation rate of 78.5% were obtained when the protoplasts were irradiated by a UV lamp of 20W in a distance of 30cm for 180s. Seven mutants were obtained, and one of them, U22, was proved genetically stable. Conclusions: The mutation induction system of P. guiyangense by UV and LiCl is successful, and can provide basis for the mutation breeding of P. guiyangense in the future.
