Interaction Between Transcriptional Activator BRI1-EMS-SUPPRESSOR 1 and HSPs Regulates Heat Stress Tolerance in Pepper

Climate change is predicted to stymie agricultural productivity in the future. To mitigate these detrimental consequences, traditional breeding and genetic engineering of environmentally tolerant plants are necessary. The discovery of genes related to stress tolerance is crucial to achieving this goal. In this study, we conducted transcriptome analyses of heat-tolerant and heat-sensitive pepper species to identify the genetic elements governing heat-stress tolerance in pepper plants. Using WGCNA (Weighted Gene Co-expression Network Analysis), we created co-expression networks from the transcriptome data and identified a heat-related module (ME.cyan), in which the BES1 transcription factor, CcBES1 (CcBES1–4), plays a central role in the heat tolerance mechanism in pepper. We successfully identified and functionally characterized the BES1 gene from the pepper. CcBES1 is predominantly a transcriptional activator encoded by a nucleus-localized protein. We generated CcBES1-silenced pepper lines and conducted heat stress assays in vitro. Dwarf-specific phenotypes and heat stress susceptibility were observed in the CcBES1-silenced line. Moreover, most of the Heat shock factor proteins (HSPs) expression in CcBES1-silenced lines were consistent with the ME.cyan module co-expression network genes. Yeast one-hybrid results revealed that CcBES1 directly binds to the putative promotor regions of the HSPs, indicating that CcBES1 controls co-expressed HSPs to govern heat stress tolerance. The findings of the present study demonstrate approaches to trigger substantial networks augmented for thermotolerance, laying the foundation for future studies into the management of heat stress regulation.