Exogenously applied methyl Jasmonate induces early defense related genes in response to Phytophthora infestans infection in potato plants

In order to elucidate the contributions of JA in orchestrating disease resistance in potato plants, the potato genotype ‘SD20’, which exhibits strong resistance against the highly virulent Phytophthora infestans isolate CN152, while infected by the super virulent isolate 2013-18-306, was treated with exogenous JA and then challenged by inoculation with 2013-18-306. The results showed that exogenously applied JA significantly delayed the onset and alleviated the symptoms of late blight, indicating exogenous JA could induce resistance to P. infestans in the early biotrophic stage of infection in ‘SD20’ plants. To further clarify the role of JA in the early defense response and identify key genes involved in JA signal transduction, gene expression profiling via RNA sequencing (RNA-seq) in ‘SD20’ plants treated with exogenously applied JA was performed. A total of 2 927 differentially expressed genes were specifically induced, the majority encoded transcription factors, protein kinases, secondary metabolites, defense enzymes and disease resistance related proteins. GO functional annotation and KEGG metabolic pathway analysis showed that exogenously applied JA rapidly induced the expression of genes related to immune response regulation, pathogen defense, and other biological processes, and stimulated endogenous JA synthesis and signal transduction, and the overall early pathogen defense response in ‘SD20’. These results provide useful information in understanding the JA's function involved in pathogen defense responses and a theoretical basis for the application of JA in potato production.