Advances in Physiological and Molecular Mechanisms of Cucumber Response to Low-Temperature Stress

Cucumis sativus L. is a globally important vegetable crop that occupies a significant position in protected agriculture due to its high nutritional value, short cultivation cycle, and considerable economic benefits. As a cold-sensitive plant, however, cucumber is highly susceptible to low-temperature stress. which can severely inhibit growth and development, hinder seed germination, and reduce photosynthetic efficiency. Under low-temperature stress, cucumber plants typically incur damage to cellular membrane structures, experience an accumulation of reactive oxygen species (ROS), exhibit a disruption in hormonal homeostasis, and suffer from the inhibition of pivotal metabolic pathways. In response, cucumber plants activate an array of resistance mechanisms, encompassing osmotic adjustment, reinforcement of the antioxidant system, and modulation of cold-responsive gene expression. This review summarizes the physiological and molecular mechanisms underlying cucumber’s response to low-temperature stress, aiming to provide effective strategies for improving abiotic stress resistance. The main findings are as follows: (1) Low-temperature stress damages cucumber cell membranes, suppresses photosynthesis and respiration, suppresses water and nutrient uptake/transport, and suppresses growth retardation. (2) Cucumber counters these adverse effects by orchestrating the accumulation of osmoregulators (e.g., soluble sugars, proline), activating activation defenses (e.g., SOD, CAT), and rebalancing its phytohormone network (e.g., ABA, GA, SA, ethylene). (3) At the molecular level, cucumber activates low-temperature-responsive genes (e.g., COR, GoIS) through transcription factors such as CBF, MYB, and WRKY, thereby enhancing cold tolerance. (4) Application of exogenous protectants (e.g., hydrogen sulfide, melatonin, oligosaccharides) significantly improves cucumber’s low-temperature tolerance by modulating the antioxidant system, promoting osmoregulatory substances accumulation, and regulating hormone signaling pathways. Future research should focus on elucidating the molecular regulatory network in cucumber under low-temperature stress and developing gene editing with multi-omics techniques to advance the development of cold-resistant cultivars and cultivation practices. This study offers a scientific foundation for research on cucumber cold tolerance and proposes potential solutions to agricultural challenges in the context of global climate change.