Identification And Preliminary Mechanism Of Biocontrol Microbial Inducing To Resistance To Wheat Leaf Rust

Wheat leaf rust(Puccinia triticina)is one of the most important diseases in wheat.The disease is distributed in major wheat areas in China and has gradually increased in recent years.The strains that could induce the wheat to generate resistance against leaf rust were selected through field and indoor pot in this paper.And the effective strains were systematically researched on its classification,control effect and inducing mechanism.Study the strain induce the wheat to generate resistance against Puccinia triticina to explore the mechanism of induced resistance at molecular level.The results were as follows:1.Screening of biocontrol strains induced resistance against leaf rust: Wheat seeds were coated by the fermentation broth of 4600 strains in field,pot test and field efficacy tests after screening.The results showed that four highly effective strains Sneb1462,Sneb1586,Snef384 and Snef570 all had good control effect on the infection of Puccinia triticina,and also had the effect of promoting the growth of wheat.2.Identification of biocontrol strains induced resistance against leaf rust: Biocontrol strains were identified by morphology and biochemical characteristics as well as 16 S r DNA sequence analysis.The results showed that Sneb1462 was Paenibacillus polymyxa,and Sneb1586 were Bacillus cereus.Sneb384 was Trichoderma atroviride,and Sneb570 was Trichoderma viride.3.Study on the change of reactive oxygen species induced by strain Sneb1462: Wheat seeds were coated with fermentation broth of strain Sneb1462 and challenged to inoculate Puccinia triticina.The content of ROS were measured at different infection stages after inoculation when the wheat seedlings grew to one leaf and one heart.The results showed that the content of O2-and H2O2 increased significantly within 48 h before strain Sneb1462 treated and inoculated,and was 1.49 and 1.62 times higher than the blank control at 12 h and 24 h respectively,indicating that bacterial Sneb1462 could induce wheat initiation and accumulation of ROS and participate in the systemic defense response of wheat in the initial stage of infection.4.Expression analysis of the defense-related genes induced by strain Sneb1462: The real-time fluorescence quantitative PCR technique was used to analyze the expression of defense-related genes at different time points after inoculation with Puccinia triticina in wheat leaves.The results showed that POD and SOD genes were significantly expressed at the initial stage after the bacterial Sneb1462 induction and inoculation treatment.The peak values were 3.11 and 7.50 times higher than the blank control.The expression of PR-1,PR-2 and PR-5 pathogenesis-related protein genes was significantly up-regulated at 12 h,which were 2.83,7.50 and 9.89 times higher than the blank control respectively,indicating that strain Sneb1462 was involved in the inducted expression of defense-related genes at the initial stage of infection,and enhanced plant resistance.