| Oyster mushroom is one of the most popular edible fungi in China and widely cultivated according to its high nutritional and medicinal value. However, in its cultivation process, oyster mushroom is often subjected to a wide range of both abiotic and biotic stresses. High temperature, as one of the abiotic stresses, limits the mycelium vitality and development, makes the mycelium vulnerable to be infected by Trichoderma spp., and finally leads to the decrease in mushroom quality and quantity. Proteomic, as the important part of functional genomics and the main technique to explore physiological mechanisms, has been successfully applied to study various systems in edible fungi.For Pleurotus spp., some problems such as heat stress response, heat resistant mechanism and the vulnerability to be infected by Trichoderma spp., have still not been cleared yet. In our study, we optimized heat treatment conditions, explored the expressions of different proteins and resistance to Trichoderma on Pleurotus cornucopiae and P. ostreatus under heat stress. The purpose of the study is to understand heat response mechanism, provid important protein information and theoretical basis for breeding heat resistant Pleurotus spp. strains with excellent agronomic traits. The results were listed as follow:(1) Based on thiobarbituric acid reactive substances content and recovery percentage as the main physiological indexes, the level of heat stress conditions for P. ostreatus CCMSSC 00389, CCMSSC 00374 and P. cornucopiae CCMSSC 03989, CCMSSC 00358, CCMSSC 00329, CCMSSC 00406, CCMSSC 00360, CMSSC 00798, CCMSSC 00324, CCMSSC 00502, CCMSSC 00454 was studied. Results showed that the heat stress conditions are optimized by using three days’mycelium as the material,12℃ higher than the optimal growth temperature for 48h treatment.(2) After different heat treatment, we found 686 proteins,204 proteins of which were differentially expressed under 40℃ for 48h and/or during the 3d recovery phase after heat stress in comparison to unstressed control respectively, in proteomic analysis by iTRAQ combined LC-MS/MS for P. ostreatus CCMSSC 00389. Stress and recovery conditions shared 47 proteins, while 84 and 73 proteins were identified under heat stress and recovery conditions, respectively. Based on GO analysis, these differentially expressed proteins were classified to 23 functional categories, of which regulatory, stress responsive and transport proteins are the three major ones in heat stress response. The subcellular localization showed these leading proteins localized in mitochondrion, endoplasmic reticulum, secretory pathway and peroxisome.(3) Four hsps genes’ expression significantly increased under heat stress using RT-PCR. The hsp60、grp78、hsp90、hsp104 genes up-regulated 28 fold,6 fold,10 fold and 15 fold under heat stress in P. ostreatus CCMSSC 00389, respectively. However, no significant differences were found after 3d recovery in comparison to unstressed control. We concluded that up-regulation of hsps genes’expression plays an important role in accumulation of heat shock proteins.(4) Pleurotus strains have different resistance ability. The infection rates of Trichoderma harzianum for CCMSSC 00360, CCMSSC 00324 and CCMSSC 00329 were 60%, which was much lower than 100% for CCMSSC 03989 and CCMSSC 00406. The cell wall and cell membrane were both damaged after treatment with 40℃ for 48h, thus CCMSSC 00389 was seriously infected by Trichoderma harzianum. After recovery 3d, the infection rate went down, which revealed that high temperature lead to large area pollution in cultivation. |
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