Transcriptome analysis revealed that grafting improves the resistance of pepper to Phytophthora capsici by fine-tuning growth-defense tradeoff

Abstract

DOI 10.15835/nbha50212705
 Grafting has been widely used to defense soil borne diseases and nematodes in vegetables production. However, the underlying mechanism of grafting-improved disease resistance is largely unknown. In this study, grafting cv. ‘Ledu’ scion to cv. ‘Jingxin No. 5’ rootstocks improved the resistance of pepper to Phytophthora capsici. To gain insights into the regulatory networks related to grafting, we performed transcriptome analysis of grafting and control pepper plants with or without P. capsici inoculation. RNA-seq analysis revealed that P. capsici infection largely re-programmed the pepper transcriptome and differentially expressed genes (DEGs) functionally annotated to metabolism processes including photosynthesis, response to stimulus, enzyme activity, and transcription were significantly enriched. Furthermore, the expression levels of most DEGs induced by P. capsici infection, such as genes functionally related to plant hormone signal transduction, plant-pathogen interaction, photosynthesis, reactive oxygen species, tend to recover to the control levels in grafting pepper plants, which help pepper maintain moderate plant defense response and considerable accumulation level of assimilation product, therefore fine-turning the dynamic balance between pepper growth-defense tradeoffs. Taken together, our results suggest the dynamic transcriptional programming in grafting pepper that underpin P. capsici disease and providing insight that the fine-tuning balance between growth and defense of grafting pepper.