Transcriptome analysis of immune and susceptible materials of pepper resistant 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 P. capsici infection. We used ZCM334 pepper material, a high generation inbred line immune to P. capsici with no infection signs 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 secondary metabolite and phenylpropanoid biosyntheses, 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, CML, MAPK, RLP, RLK, WRYK, and MYB, most of which were upregulated after inoculation. The excavation of key genes and metabolic pathways provides insights into further exploring the molecular mechanism of pepper resistance to phytophthora blight.