Heat stress resilience in Capsicum annuum: Scientific Perspectives

The anthropogenic rise in greenhouse gas emissions intensifies the trapping of longwave radiation emitted from the Earth's surface, leading to increased global temperatures. High temperatures (HT) adversely affect the critical developmental stages in chilli, such as root initiation, flowering and fruit set. In response, chilli plant employs a range of strategies including escape, acclimation and adaptation mediated by the expression of stress responsive proteins, genes and metabolites. The key components of this response include heat shock proteins (HSPs), reactive oxygen species (ROS) scavenging enzymes, aquaporins, osmoprotectants and other stress inducible genes that collectively enhance thermotolerance. Conventional breeding efforts have improved HT adaptability by selection for traits such as increased biomass, normalized difference vegetation index (NDVI) and reduced canopy temperature. In addition, landraces represent valuable genetic resources for identifying heat tolerant genotypes, and can be evaluated by advanced phenotyping platforms. Moreover, the integration of next generation sequencing (NGS) technologies with physiological data allows for the rapid and high-throughput discovery of candidate genes associated with heat stress tolerance. Molecular breeding approaches such as marker assisted selection (MAS), genomic selection and genome wide association studies (GWAS) enable the development of heat tolerant chilli cultivars in shortest time duration. This review offers an in-depth analysis of the physiological, biochemical and genetic mechanisms underlying heat tolerance (HT) in chilli, recent omics advancements and the challenges of breeding heat resilient cultivars. A deeper understanding of these mechanisms is crucial for creating robust chilli varieties capable of withstanding HT, ensuring sustainable yields and food security under changing global climatic conditions.