Comparative transcriptomics of Monilinia fructicola - resistant and - susceptible peach fruit reveals gene networks associated with peach resistance to brown rot disease

Peach brown rot, primarily caused by Monilinia fructicola, is a major cause of fruit loss during the post-harvest period. Although some varieties with improved brown rot tolerance have been identified, the genetic basis of brown rot resistance remains unclear. In this study, a comparison of the transcriptome response to M. fructicola infection in peach the resistant ‘Xiahui 8’ (XH8) and susceptible variety ‘Xiahui 6’ (XH6) indicating 622 resistance-associated differentially expressed genes (DEGs) that could be consistently detected throughout the 12–48 h postinfection period. Gene Ontology (GO) enrichment analysis of the 292 upregulated resistance associated DEGs indicated an enrichment (54/292, p＜0.05) in defense and stimulus response terms. Co-expression network analysis indicated nine gene modules of co-expressed genes, with two modules linked to PpNLR genes and showing associations with DEGs related to calcium signaling, autophagy, lignin biosynthesis, and pathogenesis-related proteins (PRs). Interestingly, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis suggested enrichment in stress-related pathways such as plant-pathogen interaction, flavonoid biosynthesis, phenylpropanoid biosynthesis and amino sugar and nucleotide sugar metabolism. Moreover, relative to XH6, M. fructicola infection of XH8 resulted in increases in the expression of PpNLRs and PpCNGCs, the induction of cell death, the activities of chitinases and β-1,3-glucanes, and the peach contents of calcium, reactive oxygen species, lignin and anthocyanins. These findings provide a greater insight into the genetic basis of peach fruit resistance to brown rot disease and can ultimately aid in breeding resistant peach varieties.