Three strains of straw mushroom, Volvariella volvacea; brown gills, Thai strain (TH); white gill, Thai strain (WG) and Taiwan strain (TA) were cultivated for 4 days. Their cell walls were lysed by mixed enzymes of zymolyase 0.2 mg/ml and cellulose 2% incubated at 30๐C 4 hours. There were 7.33x104, 8.50x104 and 8.67x104 protoplasts/ml, respectively. The each tube of protoplasts were mixed in pair in polyethylene glycol (MW .-8000) solution. The regenerating colonies were isolated and compared to the parental strains, the size of hyphae and the total DNA content. It was found that hyphae were larger and the total DNA content of fusants were higher than the parental strains. Selected fusants, which possess total DNA in double or triple times than parents, were grown on specific medium in order to induce the fruiting primordia formation. Only six strains were selected for fruiting bodies cultivation. The results showed that fusants gave higher numbers of fruiting body production, wet weight and dry weight, when compared to parents. Statistically tested showed the significant 95% of fruiting body production and dry weight. Wet weight of fruiting body was significant at 99 percentage. It found out that when compared within 6 strains, the fusant F (TA-WG6) gave the highest frequency of fruiting bodies formation and productivity.
