Deciphering the Role of Salicylate and Jasmonate in Crop Protection: Ensuring Future Food Security
Plant hormones orchestrate the defensive capacity of crops against an expanding array of biotic and abiotic constraints that threaten global agricultural output. Among these regulators, salicylic acid and jasmonic acid form the backbone of inducible immunity, directing distinct yet interconnected transcriptional programmes that determine whether a plant survives attack by biotrophic pathogens, necrotrophic fungi, phloem-feeding insects or chewing herbivores. This review synthesises current knowledge on the biosynthesis, perception and signal transduction of salicylate and jasmonate, and examines the molecular basis of their crosstalk, which ranges from mutual antagonism to context-dependent synergy. Particular attention is given to the agronomic exploitation of these pathways through exogenous hormone application, seed priming, defence elicitors and induced systemic resistance, alongside the physiological costs that accompany such interventions, most notably the growth-defence trade-off associated with sustained jasmonate signalling. The review situates this mechanistic understanding within the pressing context of global food security, considering how pest pressure, plant disease and climate-driven abiotic stress converge to erode crop yields, and how hormone-informed breeding and crop management strategies might mitigate these losses. Persistent knowledge gaps are identified concerning field-level translation, crop-specific pathway architecture in monocots relative to the Arabidopsis model, and the reconciliation of defence induction with yield stability. The review concludes that a nuanced, crop-specific understanding of salicylate-jasmonate signalling, rather than a uniform strategy transplanted from model species, will be indispensable for designing resilient cropping systems capable of sustaining production under mounting biotic and climatic pressure.