Drought-stress memory confers cold hardiness in grapefruit (Citrus paradisi) through modulations in antioxidant system, osmolyte production and carbohydrate metabolism

Authors: PEREZ, CARLOS - University Of Florida; HUSSAIN, MUJAHID - University Of Florida; IQBAL, SHAHID - University Of Florida; CHATER, JOHN - University Of Florida; BALAL, RASHAD - University Of Sargodha; Mattia, Matthew; SHAHID, MUHAMMAD - University Of Florida

Submitted to: Plant Stress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2025
Publication Date: 3/8/2025
Citation: Perez, C., Hussain, M., Iqbal, S., Chater, J.M., Balal, R.M., Mattia, M.R., Shahid, M.A. Drought-stress memory confers cold hardiness in grapefruit (Citrus paradisi) through modulations in antioxidant system, osmolyte production and carbohydrate metabolism. Plant Stress. 15:100801. 2025. https://doi.org/10.1016/j.stress.2025.100801.
DOI: https://doi.org/10.1016/j.stress.2025.100801

Interpretive Summary: Cross tolerance is a process through which plants are exposed to a stressful event and are better prepared to handle the same stress or another. In relation to cold tolerance, there is a lack of scientific knowledge regarding the drought-priming effect on the freeze tolerance mechanism in cold-sensitive citrus (grapefruit). This study was conducted to gain insight into how plants perform under cold stress when drought stress was done first. To investigate whether drought stress can serve as an indicator in cold hardiness, we subjected the cold-sensitive grapefruit (cv. Flame) plants to a drought treatment and freezing stress. Drought treated plants also showed increased carbohydrate production, sugars, and reduced starch reserves. It is concluded that drought-stress treatment helped the plants to tolerate freezing stress. Changes in internal molecules helped plants better cope with subsequent freezing stress. This corresponding response highlights the valuable impact of drought treatment in improving cold hardiness in young grapefruit plants through a comprehensive physiological and biochemical stress-alleviating mechanism.

Technical Abstract: Cross tolerance is a phenomenon through which plants are initially exposed to one type of stressful event and are better prepared better to handle the same stress or another. In relation to cold tolerance, there is a lack of scientific knowledge regarding the drought-priming effect on the freeze tolerance mechanism in cold-sensitive citrus (grapefruit). Therefore, the present study was conducted to gain insight into how plants perform under cold stress when given drought stress as a priming agent. To investigate whether pre-freezing drought stress can serve as a primer in cold hardiness, we subjected the cold-sensitive grapefruit (cv. Flame) plants to drought-priming (50%, 75% and 100% field capacity) and post-priming freezing stress (-6 °C). Drought-priming memory has been found to enhance the ability of plants to withstand freezing temperatures by regulating their antioxidant system, osmolyte production, and carbohydrate metabolism. Drought priming triggered the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione peroxidase (GPX), and ascorbate peroxidase (APX) to reduce oxidative damage caused by excessive formation of reactive oxygen species (ROS). Drought priming also accelerated the accumulation of osmolytes like proline, glycinebetaine, and soluble sugars, which help stabilize cellular structures and maintain osmotic balance under stressed conditions. Drought-primed plants also showed modulated carbohydrate metabolism, sugars biosynthesis and reduced starch reserves. It is concluded that drought-stress memory as a primer acclimated the plants to freezing stress by alleviating oxidative damage to membranes and maintained high energy production through enhanced antioxidant activities, osmolyte accumulation, and regulating carbohydrate metabolism. These adaptive changes helped plants better cope with subsequent freezing stress, improving their resilience by sustaining energy production, maintaining cellular integrity, and ensuring metabolic activity. This corresponding response highlights the valuable impact of drought priming in improving cold hardiness in young grapefruit plants through a comprehensive physiological and biochemical stress-alleviating mechanism.