Studies On Selection Of High-yielding Pleurotus Strains By Protoplast Technology

The improvement of yield and quality of edible fungi lies on the excellent strains firstly. The production of Pleurotus fungi in our country is biggest in the world.So,it is very important to breed the excellent strains deeply and punctiliously. The breeding technique of protoplast has evident characteristic of deploitation comparing with traditional mating breeding.This experiment was studied on the optimum conditions of protoplast preparation and regeneration from Pleurotus salmoneostramineus, Pleurotus ostreatus 4011, Pleurotus nebrodensis, while the breeding of high-yielding strains was studied.The result showed that both the protoplast yield and regeneration ratio were higher in Pleurotus salmoneostramineus and Pleurotus ostreatus 4011, while the protoplast yield was higher and the regeneration ratio was lower in Pleurotus nebrodensis. Further study showed the optimum enzymolysis conditions were determined by using 5-day mycelial at 28℃for 2 hours, while the protoplast was prepared with 1% cellulose and 1% helicase as lytic enzymes from Pleurotus nebrodensis.Cane sugar as osmotic stabilizer could give higher protoplast yield and regeneration ratio.The regenerating ratio could reach 2.1%,about 3 times to annitol as osmotic stabilizer.By the preparation and regeneration of protoplast from Pleurotus salmoneostramineus, a lot of fast and strong-growing strains were selected out.The excellent strains H120 and H247( F₃ generation) showed not only rapid mycelial growth rate and fewer number of bagful days ,but also higher biological efficiency and increased in yield by 14.9% to 21.7% at significant difference level compared with the original strain.A few of extracellular amylose decomposed enzyme activities of the protoplast regenerating strains from Pleurotus salmoneostramineus were mesured. The result showed that there was definite positive correlation between the activities of extracellular cellulose enzyme and mycelial growth rate.By the breeding of high quality strains from Pleurotus ostreatus 4011, the excellent strain P211 was obtained and showed difference from original strain in culture medium decompose ability. In the medium amended with corncob, not only the growth rate of P211 was rapid and the number of bagful days was fewer,but also the biological efficiency was increased by 13.1% at significant difference level comparing with the original strain. By the screening of protoplast regenerating strains from Pleurotus nebrodensis, the strain B102 was obtained and showed rapid mycelial growth rate and higher fruitbody yield, the strain B306 showed increased in yield at significant difference level comparing with the original strain.Study on esterase isoenzyme showed that the screened strains were new variant strains different from the original strain because there were some difference in their esterase isoenzyme pattern.