Gene Expression Profiling of Papaya (Carica papaya L.) Immune Response Induced by CTS-N after inoculating PLDMV.

Plant immune regulation is a defensive strategy of plants for protection against pathogen invasion, and Chitosan-N (CTS-N) can induce plant autoimmunity regulation mechanisms. CTS-N was found to induce an immunomodulatory response in papaya against Papaya leaf-distortion mosaic virus (PLDMV). To date, the gene expression profile of CTS-N-induced papaya immunomodulatory response has not been reported. Here, the transcriptional map of papaya leaf genes were subjected to three treatments, viz., non-viral inoculation without CTS-N treatment (CK), virus inoculation without CTS-N treatment (CG), and virus inoculation of 1g/L treatment (B). These were studied by pot culture experiment. Comparison of the B group with the CK group revealed 732 upregulated and 510 downregulated genes. Comparison of the CG group with the CK group revealed 909 upregulated and 1024 downregulated genes. To determine gene function, gene ontology (GO) analysis was performed, where 480 biological process genes, 256 molecular function genes, and 343 cell composition genes were differentially expressed. Kyoto Encyclopedia of Genes and Genomes (KEGG) results revealed that the top three pathways were phenylpropane biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction. Real-time Quantitative PCR (qPCR) results were consistent with the transcriptome results, with a correlation coefficient of 0.87. The results of the transcriptional group showed that genes associated with plant resistance were induced by CTS-N-treatment in papaya. The chitinase gene was related to the plant disease process. Related genes in plant hormone signal transduction pathways are associated with plant resistance, and six differentially expressed genes were correlated with enhanced immune resistance in papaya.