Rethinking Proline in Orchard Agroecosystems: A Cross-Disciplinary Case for Bridging Plant Physiology, Insect Physiology and Immunity Through One Health

The roles of proline in stress tolerance, energy metabolism, immune function, and ecology across organisms suggest a broader relevance in orchard agroecosystems than is often recognized. In fruit trees, stress-induced proline accumulation reflects a complex regulatory network, while evidence also indicates that inter-organ transport contributes to protective responses under abiotic stress. In insects, proline functions as an oxidative substrate priming the rest-to-flight metabolic transition in pollinators and pests, a cryoprotective osmolyte and a structural element of conserved classes of antimicrobial peptides against microbial threats. These roles create paradoxical orchard-scale feedbacks while a stress-protective molecule both intensifies herbivore pressure and enhances pollination and biocontrol services. The orchard environment represents a meeting point of plant, environmental, animal and human health, reflecting the integrative logic of the One Health framework, where proline emerges as a highly water-soluble and bioactive compound. The functional homology between insect and human proline catabolism emerges governance-critical issues across tree physiology, insect immunity and human dietary exposure. The targeted application offers a unifying framework for farmers, scientists and policymakers to advance Sustainable Development Goal commitments across food security, human health, climate resilience and biodiversity. We conclude that proline supplementation in orchards requires regulatory monitoring across ecophysiological and pharmaceutical dimensions.