| Soybean is one of the important grain crops in our country,increasing its yield and quality is very important for our country food security.Soybean is easily threatened by various pests and diseases during the growth process affecting soybean production seriously.The disease caused by soybean bacterial spot disease is one of the common diseases in China,which seriously endangers soybean production.The disease is caused by Pseudomonas syringae pv.glycinea(Pgy).AvrB and COR are two virulece factors of Pseudomonas syringae.AvrB is a type III effector protein secreted by Pgy.And COR mimicing JAs is a phytotoxin produced by Pseudomonas syringae,including Pgy and Pto(Pseudomonas syringae pv.tomato),both of which work together to promote bacteria virulence to during infection.Considering both Pto and Pgy producing COR,the question is why Pgy is a virulence bacteria to soybean,but Pto is not? Would Pto be a virulent bacteria if carring AvrB secrected by Pgy?Plants under the biotic and abiotic stresses can cause a series of defense responses of plants.Studying the defense responses induced by plants under biotic stress is beneficial to understand the disease resistance mechanism of plants.In this study,the susceptible soybeans were used to analyze the gene expression changes under biotic stress at the transcriptional level,and the function annotation,functional classification and metabolic pathway enrichment of differentially expressed genes were explored.The response of soybean to the gene level under biotic stress was explored,and some differentially expressed genes were identified.The results of RNA-seq sequencing showed that AvrB and COR can induce Pto to activate jasmonic acid,auxin,abscisic acid and other hormonal pathways,thereby enhancing the pathogenicity of bacteria.AvrB inhibits the synthesis of flavonoids and glutathione transferase to inhibit plant detoxification,while COR activates the expression of related pathway genes.Pto and Pto(AvrB)caused oxidative stress on plants and enhanced the activity of peroxidase and superoxide dismutase.Among them,Pto(AvrB)treated soybean had the highest activity.The activity of oxidase was also increased in Pto compared with the control group,indicating that the stress of Pto and Pto(AvrB)increased the activity of plant-associated oxidase and thus better adapted to the environment.Pto treatment of soybeans increased the soluble sugar content of soybeans,while Pto(AvrB)reduced the soluble sugar content of soybeans.The results of detection of salicylic acid in soybean showed that Pto-induced resistance reaction in soybean depended on salicylic acid induction.AvrB promoted the toxicity of pathogenic bacteria by inhibiting salicylic acid-induced resistance reaction in soybean,and could affect the content change of secondary metabolites in soybean to inhibit immune reaction in soybean.In this study,the interaction system of Pseudomonas syringae pv.tomato-soybean was taken as the research object.Molecular biology,plant physiology and plant pathology were used to analyze how Pseudomonas syringae regulates secondary metabolites and hormone signal transduction pathways in soybean by using effector AvrB and coronatine.The pathogenic mechanism of AvrB and COR in the process of soybean bacterial spot pathogen infecting soybean was revealed.Our research results have important practical significance for revealing the signal pathway of soybean disease resistance and guiding soybean disease resistance breeding in the future. |
