Cold stress represents a critical constraint on crop productivity, particularly in temperate climates. Despite the established role of abscisic acid (ABA) in cold stress responses, the precise mechanisms through which transcription factors mediate ABA-dependent cold tolerance remain elusive. Here, we identify VaMYB4a, a MYB transcription factor from Vitis amurensis Rupr. (Amur grape), as a key regulator of cold tolerance. It integrates ABA signaling with the CBF (C-repeat binding factors)-COR (cold-regulated) pathway to orchestrate cold stress adaptation. Through a combination of overexpression and CRISPR/Cas9-mediated knockout lines in Arabidopsis thaliana, grape callus, and Vitis vinifera L. seedlings, we demonstrate that VaMYB4a enhances freezing tolerance by promoting osmotic regulation, reactive oxygen species (ROS) scavenging, and stomatal closure. VaMYB4a functions as a homo-dimer, with its C-terminal domain being essential for transcriptional activation. Mechanistically, VaMYB4a directly upregulates CBF and COR genes while fine-tuning ABA signaling components such as ABI1 and ABF4. Notably, ABA exhibits a dual role: enhancing VaMYB4a-mediated freezing tolerance under short-term stress but attenuating its effects during prolonged cold exposure, revealing an intricate regulatory crosstalk between cold and hormonal pathways. Our work not only advances the molecular understanding of cold adaptation but also provides a promising genetic target for developing stress-resilient grape varieties to mitigate the impacts of climate change.

Horticultural crops suffer massive production losses due to abiotic stress, which is a key limiting factor worldwide. The ability of these crops to withstand such stress has been linked to melatonin, a biomolecule with significant roles in both physiological and molecular defense responses. Melatonin is pivotal in enhancing the resilience of horticultural crops to abiotic stress, making it a critical component in their survival strategies. The application of exogenous melatonin improves abiotic stress tolerance by preserving membrane integrity, maintaining redox equilibrium, scavenging reactive oxygen species effectively, activating antioxidant defense mechanisms, and elevating gene expression related to stress responses. Furthermore, the integrated management of melatonin with other phytohormones demonstrates its potential relevance in addressing various stresses across a wide range of horticultural crops. Therefore, it is crucial to elucidate the physiological and molecular processes involving melatonin in abiotic stress in these crops. Here, we discuss current studies on the use of melatonin in horticultural crops in response to abiotic stresses, and explores future research directions and potential applications to enhance the productivity and abiotic stress tolerance of horticultural crops.