Transcriptome analysis provides new insights into the resistance of pepper to Phytophthora capsici infection

Phytophthora blight is a highly destructive soil-borne disease caused by Phytophthora capsici Leonian, which threatens pepper production. The molecular mechanism of pepper resistance to phytophthora blight is unclear, and the excavation and functional analysis of resistant genes are the bases and prerequisites for phytophthora blight-resistant breeding. We aimed to analyze the expression patterns of key genes in the plant-pathogen interaction metabolic pathway and propose a working model of the pepper defense signal network against Phytophthora capsici infection.

The 'ZCM334' pepper material used in this study is a high-generation inbred line that is immune to Phytophthora capsici and shows no signs of infection after inoculation. Comparative transcriptome analysis of the roots of 'ZCM334' and the susceptible material 'Early Calwonder' revealed significant differences in their gene expression profiles at different stages after inoculation. Most differentially expressed genes were significantly enriched in the biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, plant-pathogen interaction, and fatty acid degradation metabolic pathways. Some defense genes and transcription factors significant in pepper resistance to phytophthora blight were identified, including PR1, RPP13, FLS2, CDPK, CML, MAPK, RLP, RLK, WRYK, ERF, MYB, and bHLH, most of which were regulated after inoculation. A working model was constructed for the defense signal network of pepper against Phytophthora capsici.

These data provide a valuable source of information for improving our understanding of the potential molecular mechanisms by which pepper plants resist infection by Phytophthora capsici. The identification of key genes and metabolic pathways provides avenues for further exploring the immune mechanism of 'ZCM334' resistance to phytophthora blight.