Non-classical Secretion Characteristics And Pathogenic Function Of The Extracellular Protein VdAcb1 Of Verticillium Dahliae

Verticillium dahliae is a soil-borne plant pathogen with a wide range of hosts and can infect hundreds of dicotyledons including cotton,potato,tomato,lettuce and many other important economic crops.Plants,which cause the symptoms of chlorosis and wilting,browning of vascular bundles,and slow growth of host plants are important plant pathogens that restrict agricultural production.Verticillium dahliae contains a large number of pathogenic genes,and its secreted protein,as an important functional element of the interaction between pathogens and hosts,has been a hot spot in the field of plant pathology in recent years.Compared with the great progress made in the analysis of the pathogenic mechanism of classical secreted proteins,there are fewer studies on non-classical secreted proteins.Acetyl-Co A-binding protein(Acb A)is the most intensively studied non-classical secreted protein.Its research has been carried out in yeast and Dictyostelium discoideum,and the results show that Acb A is a non-classical secreted protein,and its secretion depends on GRASP.In addition,Acb A is also related to lipid metabolism,sporulation and mycelial growth.However,the function of Acb A in Verticillium dahliae has not been reported.Therefore,this article focuses on the secretion characteristics and pathogenic function of Verticillium dahliae Acb A(VdAcb1).The main research results obtained are as follows:1.The yeast signal trap assay proved that VdAcb1 lacks the signal peptide domain.Western blot results show that VdAcb1 can be detected in the culture medium of Verticillium dahliae;laser confocal microscope observation results show that VdAcb1-GFP can be transported to the periphery of host epidermal cells during the infection process,but it lacks the Golgi accumulation protein Vd GRASP invasion.Staining causes the fluorescence signal to decrease.It shows that VdAcb1 is a non-classical secreted protein,and its secretion is regulated by Vd GRASP but not by VdATG1.2.In order to further study the function of VdAcb1,the VdAcb1 deletion mutant?Acb1 and the functional complement mutant were constructed through genetic transformation by Agrobacterium-mediated homologous recombination,and the growth phenotype and sporulation rate were determined.Affect the basic growth and spore-producing ability of Verticillium dahliae.3.The expression of VdAcb1 gene was significantly up-regulated during the process of cotton infection.Pathogenicity experiments showed that the pathogenicity of ?Acb1 to cotton and tobacco was significantly lower than that of the wild type.The deletion of VdAcb1 gene affected the growth of Verticillium dahliae in the host.Colonization indicates that VdAcb1 plays an important role in the pathogenic process of Verticillium dahliae and is necessary for pathogenicity.Cellulose membrane penetration experiments showed that the deletion of VdAcb1 gene did not affect the penetration ability of Verticillium dahliae.The effect of VdAcb1 on the utilization of carbon source was analyzed,and the results showed that ?Acb1 grew slowly on pectin medium compared with wild type.Further analysis found that pectin treatment can increase the expression level of VdAcb1 gene.In addition,the detection of pectin degradation and utilization related gene levels found that the expression levels of pectin degradation and utilization genes in ?Acb1 were significantly higher than those of the wild type.The above results indicate that VdAcb1 participates in the influence of the use of pectin by Verticillium dahliae in the infection process.In summary,VdAcb1 is a non-classical secreted protein,and its secretion is regulated by Vd GRASP but not by VdATG1.VdAcb1 affects the utilization of pectin by Verticillium dahliae,improves the adaptability of pathogenic bacteria to the infection environment,and ultimately affects the pathogenic function of Verticillium dahliae.