The Study On Physiological Mechanism Of Trichoderma-infection Caused By High Temperature Stress In Pleurotus Ostreatus Cultivation

In China,Pleurotus ostreatus is mainly cultivated in plastic house,which is easily influenced by environmental conditions,and a large area of Trichoderma-infection occurs frequently.The outbreak of Trichoderma-infection seems to be relative to the hot weather according to the grower experience in the cultivation.However,it has not been confirmed by experiments,and the mechanism of the outbreak of Trichoderma-infection caused by high temperature has not been reported.The main cultivar,P.ostreatus CCEF 89?CCMSSC 00389?and T.asperellum?ACCC 32725?which was isolated from the infected culture bag were used to study the outbreak mechanism on Trichoderma-infection cuased by high temperature in P.ostreatus cultivation.The main results are as follows:1.The resistence of P.ostreatus mycelia to Trichoderma-infection was decreased after they suffered from high temperature.The results were as follows:?1?The adsorbtion to T.asperellum conidia apparently increased.?2?A total of 141 diffferential metabolites were identified,including organic acids,amino acids,amines,glycosides,esters,polysaccharides,alcohols,etc.The extracellular fluid and differential metabolites can promote the mycelial growth and conidial germination of T.asperellum.?3?High temperature can destroy the cell wall integrity of P.ostreatus.A large amount of chitin deposition were formed on the surface of the mycelia.The cell walls were thicker,but the cell wall structure was sparse.The characteristic absorption peak of glucosidic bond which linked between?-glucan was decreased,and the structure of?-glucan itself was damaged,the crosslinking was loose and the cell wall was fragile.The content of mannose in the cell wall was significantly decreased,and the cell wall porosity was increased.P.ostreatus mycelia were more sensitive to cell wall perturbing agents?CFW,SDS,CR?at high temperature.The cell wall structure tended to shrink,the surface was rough and incomplete.?4?The ability of P.ostreatus mycelia to resist Trichoderma lyzing enzyme were significantly decreased.2.The infectivity of T.asperellum was significantly enhanced after high temperature.The results showed that?1?Conidial germination rate increased significantly.?2?The time of conidium formation was greatly shortened.?3?The mycelium of P.ostreatus increased the activities of Trichoderma cell wall degrading enzyme?chitinase,beta glucan enzyme and protease?,and the promoting effect of P.ostreatus mycelia subjected to high temperature was stronger.3.There were significant differences in the degree of damage caused by high temperature between P.ostreatus and T.asperellum.T.asperellum mycelia had a significantly higher tolerance to high temperature than P.ostreatus.Under high temperature,extracellular H₂O₂ increased during Trichoderma-infection,and high concentration of H₂O₂ will further inhibited mycelial growth of P.ostreatus.The experiment of various types of metabolites showed that the metabolites with high concentration after high temperature stress could almost promote the mycelial growth and the conidial germination of Trichoderma.Conclution:it was clear that the key factor of Trichoderma-infection in bags—suffered from high temperature during spawn running.Three physiological mechanism of the outbreak of Pleurotus green mold disease caused by high temperature was clear:The resistance of P.ostreatus was decreased,and it was easy to be infected.The infection ability of Trichoderma was enhanced,and high temperature was beneficial to the inhibition and infection of Trichoderma to P.ostreatus.