Cold stress tolerance in pepper: role of transcription factors in molecular signaling and adaptive responses

Abstract

Pepper (Capsicum annum L.) is an important horticultural commodity known for its nutritional and medicinal properties. However, cold stress severely hinders its growth, development, and productivity, posing a major challenge to stable production in many cultivation regions. Cold stress disrupts membrane integrity and impairs photosynthesis, cellular homeostasis, and osmotic balance, while also promoting excessive accumulation of reactive oxygen species (ROS), leading to oxidative damage and metabolic imbalance. To mitigate these adverse effects, pepper plants initiate complex molecular signal transduction pathways, which are controlled by transcription factors (TFs) that regulate the expression of stress-responsive genes. Major TF families involved in cold stress responses include MYB, WRKY, Cys2/His2-type zinc finger protein (C2H2), NAC, Phytochrome-Interacting Factor (PIF), C-repeat Binding Factor/Dehydration-Responsive Element Binding protein (CBF/DREB), and bHLH. These genes are responsible mainly for perceiving and transmitting cold signals in pepper via abscisic acid (ABA)-mediated and ABA-independent pathways, calcium–mitogen-activated protein kinase (MAPK) cascades, ROS signaling, and hormone regulation. Functional investigations have revealed that multiple TFs, such as CaNAC064, SNF1-Related Protein Kinase 2.4 (CaSnRK2.4), CaNAC035, CaCBF1B, CaWRKY40, and CaMYB80, are essential positive regulators of cold tolerance, resulting in improved scavenging of ROS, osmotic balance, and membrane integrity. Recent advances in genomics and transgenic strategies, such as CRISPR/Cas-based genome editing, has further elucidated these TF-mediated regulatory pathways, providing potential approaches for developing cold-tolerant pepper cultivars. By elucidating the molecular mechanisms underlying cold stress responses, it offers key perspectives for the breeding of climate-tolerant pepper varieties to ensure sustainable agricultural production.