A new study demonstrates that proline biostimulation can significantly enhance freezing stress tolerance in citrus by stabilizing photosynthesis, strengthening antioxidant defenses and improving carbohydrate metabolism. The findings offer promising strategies for protecting citrus crops from damaging low-temperature events.
Proline biostimulation is the application of the amino acid proline to plants to help them resist harsh environmental conditions like freezing cold, drought and high salt. It works by stabilizing plant cells, boosting internal defenses and improving energy use.
Carlos Eduardo Aucique-Perez, Shahid Iqbal, John M. Chater and Muhammad Adnan Shahid with the University of Florida Institute of Food and Agricultural Sciences along with Rashad Mukhtar Balal with the University of Sargodha in Pakistan authored an article about the study.
Freezing stress is a major constraint on citrus production, often causing cellular damage, reduced photosynthetic efficiency and yield losses. In this study, researchers evaluated how exogenous proline application influences citrus physiological and metabolic responses under freezing conditions. Results showed that proline-treated plants maintained higher photosynthetic performance and membrane stability compared with untreated plants exposed to cold stress.
Proline biostimulation was also associated with enhanced antioxidant activity, reducing the accumulation of reactive oxygen species typically induced by freezing temperatures. This strengthened antioxidant defense helped limit oxidative damage to plant tissues during stress events.
In addition, proline-treated citrus plants exhibited coordinated regulation of carbohydrate metabolism. Improved sugar accumulation and utilization supported energy balance and osmotic protection, further contributing to cold tolerance and post-freeze recovery.
Together, these coordinated responses highlight proline’s role as an effective biostimulant for improving citrus resilience to freezing stress. The findings suggest that proline-based treatments could be a practical management tool to mitigate cold injury in citrus-growing regions increasingly affected by unpredictable temperature extremes.
See the full article in the Journal of the American Society for Horticultural Science.
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