Study On The Control Effect And Mechanism Of Two Antagonistic Srains On Asarum Leaf Blight

Asarum is a commonly used Chinese medicinal material.Leaf blight is the main disease in the production of asarum,with a high incidence and serious harm,which seriously affects the yield and quality of medicinal materials.At present,the main cause of asarum leaf blight is chemical control,which is likely to cause pathogen resistance enhancement,environmental pollution,and food safety issues.Biological control has the advantages of no pollution,no residue and ecological safety,and has obvious advantages in plant disease control.In this paper,two antagonistic strains were selected from the rhizosphere soil of asarum healthy plants by the methods of confrontation culture and antagonistic fermentation liquid culture,and their control effect in vivo was measured;Then,physiological,transcriptome and proteomic techniques were used to study the control mechanism of antagonistic strains.The main results are as follows:1.Screening of antagonistic strain and determination of their control effectMore than 100 colonies were isolated from the rhizosphere soil of healthy plants of asarum,and through the confrontation test and the fermentation liquid fungistasis test,obtained antagonistic fungi F1-6 and antagonistic bacteria S2-31 strains with higher inhibitory effects on asarum blight.The fungistasis rates of the confrontation culture test were 61.25 % and 92.47 %,the fermentation broth fungistasis tests were 63.64 % and 60.56 %,and the potting control effects were 70.78 % and 79.87 %,respectively.Through morphological and molecular biological identification,F1-6 strain was identified as Penicillium janthinellum,and S2-31 strain was identified as Brevibacillus laterosporus.2.Study on the control mechanism of antagonistic strainsThrough the confrontation culture of Penicillium janthinellum F1-6 and Brevibacillus laterosporus S2-31 with leaf blight fungus,respectively.The edge hyphae of the leaf blight fungus colonies were broken,shrunken and formed a large amount of chlamydospores,indicates that the growth of pathogenic mycelium was inhibited.When asarum leaves were inoculated with Penicillium janthinellum F1-6 and Brevibacillus laterosporus S2-31,defense-related enzyme activities were significantly increased,such as PPO,PAL,POD and SOD,indicating that F1-6 and S2-31 enhanced the ability of asarum to resist the infection of the pathogen of leaf blight.The transcriptome and proteomics techniques were used to analyze the changes of gene and protein expression levels in asarum leaves after two antagonistic strains treatments.The results showed that Penicillium janthinellum and Brevibacillus laterosporus can induce up-regulated expression of disease resistance-related genes and proteins in asarum leaves,and some of the up-regulated genes in the transcriptome have a confirmed relationship with the up-regulated proteins in the proteome.For example,peroxidase and its genes,and coffee acyl-coenzyme AO-methyltransferase and its genes were significantly up-regulated.The KEGG pathway enrichment analysis results of differentially expressed genes and differentially expressed proteins showed that the pathway of phenylpropanoid biosynthesis and stilbenoid,diarylheptanoid and gingerol biosynthesis were significantly enriched in F1-6 and the S2-31 treatment group.In addition,diterpenoid biosynthesis and isoquinoline alkaloid biosynthesis pathway were also significantly enriched in F1-6 treatment group;The flavonoid biosynthesis and plant-pathogen interaction pathway in S2-31 treatment group were more significantly enriched;It shows that both antagonistic strains can enhance the disease resistance of asarum by inducing gene expression and protein synthesis of resistance-related pathways.The transcriptomics technique was used to analyze the changes of gene expression level in asarum leaf blight pathogen after two antagonistic strains treatments,the results showed that two antagonistic strains can regulate the gene expression level of metabolism and genetic information processing pathways in hyphae of leaf blight pathogen.The pathways of DEGs enrichment after antagonistic strains treatment mainly include peroxisome and spliceosome pathways.The key genes involved in these pathways were down-regulated to varying degrees,such as PEX19,precursor mRNA splicing factor,splicing factor 3b,and α / β hydrolase and other coding genes.The results showed that the two antagonistic strains can inhibit the growth of mycelia of leaf blight pathogen by regulating the gene expression of the pathway related to the mycelial growth.