撑绿杂交竹基腐病生防菌的促生机制OA北大核心CSTPCD

[Objective]This study aims to explore the growth-promoting characteristics and mechanisms of two screened antagonistic bacteria,Bacillus velezensis BD2231 and Streptomyces mirabilis BD2233,so as to provide effective microbial agents for controlling basal rot of hybrid bamboo and enhancing plant growth.[Method]Qualitative and quantitative methods were used to determine the abilities of BD2231 and BD2233 in the secretion of indoleacetic acid,phosphorus solubilization,iron carrier production,biological nitrogen fixation,ACC deaminase production,and cellulase production,and to analyze the effects of the two strains on the germination of tomato and tobacco seeds,as well as on the growth of tomato,tobacco,and hybrid bamboo seedlings.ELISA kits and real-time fluorescence quantitative PCR method were used to investigate the effects of the strains on the concentrations of IAA,GA,SA,and JA and the expression of their related genes in the leaves of tomato,tobacco,and hybrid bamboo.[Result]Both BD2231 and BD2233 were able to produce IAA,iron carrier,and cellulase,but did not have the ability of phosphorus solubilization,biological nitrogen fixation,and ACC deaminase production.BD2233 secreted IAA at a concentration of 12.44 mg·mL-1,and BD2231 achieved the carrier activity unit(SU value)of 26.7%and cellulase activity(CMC enzyme activity)of 0.43 U·mL-1,respectively.Two strains of biocontrol bacteria significantly promoted the germination of tomato and tobacco seeds,and the germination rates of tomato and tobacco seeds treated with the fermentation broth of strain BD2231 were higher,at 61%and 87%,respectively.In addition,the two strains significantly promoted the growth of hybrid bamboo seedlings and increased the plant height,stem thickness,fresh and dry weight.BD2231 and BD2233 significantly promoted the expression of endogenous hormones,such as IAA,GA,SA,and JA,pathway-related genes IAA9,GA20ox,PR-1,and MYC2 in plant leaves and increased the concentration of endogenous hormones.BD2233 was more effective in improving the concentration of IAA,while BD2231 was more effective in increasing the concentration of GA,SA,and JA in plants.[Conclusion]B.velezensis BD2231 and S.mirabilis BD2233 promote plant seed germination and seedling growth through the production of IAA,iron carrier,and cellulase.They can also increase the concentration of IAA,GA,SA,and JA,as well as the expression of their related genes,with BD2231 performing better in promoting plant growth.