Cold stress, especially during chilling (0–15°C) and freezing (<0°C) conditions, disrupts plant growth and leads to substantial agricultural losses. Plants respond via complex networks involving transcription factors (TFs), such as those from the MYB family, which regulate downstream cold-responsive genes and antioxidant defenses. Among these TFs, R2R3-MYBs are particularly known for their role in modulating tolerance to various abiotic stresses. In pepper (Capsicum annuum), which thrives in warmer climates, unexpected cold events can hinder development and productivity. Although MYB TFs have been linked to cold tolerance in other species, their exact role in pepper’s response remained unclear. Due to these challenges, it is necessary to conduct in-depth research on the regulatory mechanisms of cold tolerance in pepper.
Researchers from Sichuan Agricultural University have unveiled new insights into the molecular response of pepper to cold stress. Their study (DOI: 10.1093/hr/uhae219), published on August 6, 2024, in Horticulture Research, reveals how the transcription factor CaMYB80 enhances cold tolerance by directly activating CaPOA1, a gene linked to reactive oxygen species (ROS) scavenging. The team validated their findings using gene silencing and overexpression in pepper, Arabidopsis, and tomato plants, uncovering a novel regulatory mechanism that integrates antioxidant defense with cold-responsive gene networks.
The study first identified CaMYB80 as a cold-responsive gene highly expressed in pepper under low-temperature conditions. The gene product was shown to localize in the nucleus and exhibit transcriptional activation. Silencing CaMYB80 reduced photosynthetic efficiency and antioxidant enzyme activity under cold stress, while increasing ROS accumulation and leaf damage. In contrast, transgenic Arabidopsis and tomato plants overexpressing CaMYB80 showed enhanced cold tolerance, higher antioxidant enzyme levels (SOD, POD, CAT), and less cellular damage.
Mechanistically, CaMYB80 was found to directly bind the promoter region of CaPOA1, a peroxidase gene involved in ROS detoxification. Dual-luciferase assays, GUS staining, yeast one-hybrid (Y1H), and electrophoretic mobility shift assays (EMSA) confirmed this direct interaction. Overexpressing CaPOA1 in Arabidopsis improved freezing tolerance, while silencing it in pepper led to increased susceptibility. The researchers further demonstrated that CaMYB80 activates genes in the ICE-CBF-COR regulatory cascade, a well-known cold response pathway, thus integrating ROS management with cold signaling.
Together, these findings highlight a dual role of CaMYB80 in enhancing cold tolerance by both improving ROS scavenging and promoting stress-responsive gene expression.
“Our results provide compelling evidence that CaMYB80 acts as a master regulator linking cold stress perception to antioxidant and transcriptional responses,” said Dr.Huanxiu Li, the corresponding author of the study. “By directly activating CaPOA1, this transcription factor not only reduces oxidative damage but also primes the plant for improved cold survival. These discoveries offer a promising genetic strategy for developing pepper and other crops with enhanced resilience to climate variability.”
This study paves the way for breeding cold-resistant pepper cultivars by targeting the CaMYB80–CaPOA1 regulatory module. Enhancing the expression of these genes through molecular breeding or gene editing could fortify plants against the increasing frequency of cold stress events caused by climate change. Beyond pepper, this research also provides a valuable framework for improving abiotic stress tolerance in other crops using similar transcription factor–enzyme regulatory pairs. By integrating antioxidant defense and cold-response gene networks, this discovery offers a holistic approach to engineering resilient crops for sustainable agriculture.
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References
DOI
10.1093/hr/uhae219
Original Source URL
https://doi.org/10.1093/hr/uhae219
Funding information
This work was supported by breeding research in vegetables (2021YFYZ0022).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.