Abstract
Hybrid strains of Pleurotus ostreatus were produced by intraspecific protoplast fusion crf auxotrophic mutants derived from monokaryotic strains. Auxotrophic mutants were obtained by treating fragmented mycelia by N-methyl-N'-nitro-N-nitrosoguanidine. One of them obtained from 241 ss 8 strain required uracil for growth on minimal medium, and another one obtained from 235 pSA strain required methionine. After fusion of mixed protoplasts of these two auxotrophic mutants by polyethylene glycol, many colonies were formed on a plate containing minimal agar medium. By isolating those colonies, several dikaryotic strains were obtained. They were cultured in sawdust-rice bran medium at 25C. After transfering into a condition alternating in temperature and light condition in cycle, fruit bodies were formed. Color of the fruit body was gray which was the similar color to one of the parent FMC 241, while the temperature for primordia formation of those fruit bodies was similar to the other parent FMC 235. Thus, the hybrid strain had the characteristics of both parents. Analysis of esterase isozyme pattern also showed the hybrid nature.
