The Function And Mechanism Of Trehalose-6-phosphate Phosphatase In The Process Of Anti-inverse And Infection Of Beauveria Bassiana

Beauveria bassiana,a filamentous entomopathogenic fungi,as an important biological control agent is widely used in the world.However,the field stability and insecticidal velocity of microbial fungi are still unsatisfactory and have become an important factor affecting the application of fungal insecticides.Trehalose can not only be used as an important carbon source in vivo,but also plays an important role in the environmental stress response of many organisms.In biosynthesis pathway in fungi of trehalose-6-phosphate phosphatase enzyme（TPP）catalyzes the synthesis of trehalose from Trehalose 6-phosphoric acid,and the biosynthesis pathway of trehalose in B.bassiana is an important factor for regulating the growth,resistance and pathogenicity of fungi,but there are limited reports on the biological function of trehalose metabolism in biological antifungal fungi.Taking the trehalose-6-phosphate phosphatase gene as the starting point,this paper uses homologous recombination to knock out the BbTpp gene,and through the influence of the absence of Tpp gene on the resistance and virulence of the strain,the functional mechanism of the BbTpp is analyzed,which provides a new idea for the strain improvement.The main research contents and results are as follows:（Ⅰ）Through analysis of the size,yield and germination rate of conidium,it was difficult forΔBbTpp to produce conidium during culture on SDAY plate,and the yield of spores in 7 days decreased significantly by 98.1%compared with WT.In the determination of germination rate,the conidium GT₅₀ was extended by 6.5%inΔBbTpp strain compared with WT.In the experiment of colony area,the colony area ofΔBbTpp colony area on different carbon and nitrogen source medium plates derived from 14 kinds of CZP was reduced 68⁸3%.In the experiment of spore size,the size and complexity ofΔBbTpp strains increased significantly by 11%and 50 different from that of WT,respectively,which showed that BbTpp regulated the spore yield and spore quality of B.bassiana.（Ⅱ）By measuring the content of trehalose of B.bassiana,the content of trehalose inΔBbTpp decreased significantly by 96%compared with that of WT,and there was little trehalose production in knockout strains,which verified that the TPP was involved in the synthesis of trehalose,which showed that BbTpp was necessary for the synthesis of trehalose in the B.bassiana.BbTpp mainly regulates the accumulation of trehalose by adjusting the way of trehalose synthesis,thus affecting the resistance and virulence of B.bassiana.（Ⅲ）In the experiment of chemical stress,the sensitivity ofΔBbTpp to different chemical stresses was higher than that of WT,the EC₅₀ of oxidant H₂O₂ and menadione were 20%and 27%lower than that of WT,respectively.ΔBbTpp to the cell wall interference stress of Congo red decreased 18%.In the experiment of high temperature stress and UV-B radiation,the tolerance ofΔBbTpp to ultraviolet radiation stress was20%lower than that of WT,and the LT₅₀ of 45°C high temperature stress was 15%lower than that of WT.ΔBbTpp knockout strains in the oxidation resistance,heat resistance and UV resistance and other external stress pressure has been reduced.（Ⅳ）Finally,in virulence biometrics through body wall infection,the absence of BbTpp led to the extension of LT₅₀ from 4.3 to 8.3 days.Through the blood injection,the absence of BbTpp caused the death of 50%large wax borer larvae LT₅₀ from 4.8 d extended to 5.8 d.The virulence ofΔBbTpp knockout strains decreased significantly,which indicated that BbTpp affected the potential of spore bacillus to a large extent.Altogether,Tpp plays roles in sustaining trehalose synthesis,conidiation capacity,conidial quality,multiple stress tolerance,and virulence,highlighting a significance of both for the fungal adaptation to environment and host.