Evaluation of mTERF gene expressions in response to Phytophthora capsici infection in pepper (Capsicum annuum L.) cultivars

Abstract

Despite resistance to abiotic stresses, some plant species may still show low resistance to pathogens. This biotic stress resistance can provide advantage and increase productivity in agricultural systems. However, while there is extensive research on the pathways involved in abiotic stress tolerance, the impact on the molecular mechanisms underlying pathogen resistance remains poorly understood. Among the pathogens, Phytophthora capsici, an oomycete, causes severe damage as plant pathogen, leading to blight and fruit rot in pepper and other commercially valuable crops. This study investigates the effects of Phytophthora capsici infection on highly resistant (CM334) and susceptible (Sera Demre) pepper varieties. We examined biochemical changes and gene expression across different vegetative periods (seedling, flowering, and fruiting stages). Specifically, we analyzed biochemical pathways and the mitochondrial transcription termination factor (mTERF) gene regions associated with pathogenicity. In pepper seedlings infected with P. capsici, peroxide levels increased at all developmental stages compared to control groups. Additionally, we observed a rise in H2O2 content, a molecule involved in signal transduction, likely due to the oxidative stress caused by the pathogen. The expression patterns of mTERF genes varied significantly depending on both pathogen application and the developmental stage of the plants. In the seedling stage, inoculation with P. capcici resulted in decreased expression of TERF2, mTERF6, and mTERF8 genes in leaf parts of both resistant and susceptible varieties. However, mTERF28 expression showed a significant increase. Interestingly, mTERF14 and mTERF27 gene expressions increased in the resistant variety but decreased in the susceptible one. These findings, although not providing a complete picture of host resistance mechanisms, highlight the crucial role of specific plant genes in the defense pathways against Phytophthora capsici. This knowledge can contribute to selecting pepper varieties with sustainable resistance to this devastating pathogen.