Abstract: ObjectiveBiological characteristics of degenerated strains and normal strains of Pleurotus pulmonarius were compared and double-stranded RNA(dsRNA)virus detection was conducted to offer references for choosing pre-mium strains in cultivations of P.pulmonarius.MethodAntagonism reaction test,mycelium growth rate and fruiting ex-periment were carried out on degenerated strains,and its biological characteristics were compared to the normal stains.By amplification of ITS,difference comparison were carried out using RAPD,ISSR and SRAP molecular marker.The rea-sons of degradation of P.pulmonarius were studied by dsRNA virus detection.ResultAntagonism reaction was found be-tween degenerated strains(X9 and X13)and normal strains(X5,X6 and X15).When pH of culture medium was lower than 5,the mycelium growth rate of degenerated strains significantly(P<0.05,the same below)decreased.The mycelium growth rate(4.95 mm/d),normal temperature fruiting yield per bag(73.34 g/bag)and low temperature stimulate fruiting yield per bag(107.69 g/bag)of degenerated strains X13 were significantly lower than those of normal strains and control strains.According to molecular marker analysis,there was no genetic difference among the tested strains.dsRNA frag-ments were found in all tested strains through dsRNA virus detection.Specific dsRNA fragments were detected in degene-rated stain X13.ConclusionThe degenerated strains of P.pulmonarius may be affected by dsRNA virus,resulting in weak ability to adapt to the environment and low yield.Strain source should be attached great importance to and degenera-ted stains should be avoided during cultivation.