Towards a Mechanistic Convergence Framework for Plant Biostimulant Activity: A Review of Insights from Molecular Signalling, Multi-Omics and Plant Physiology

Abstract

Plant biostimulants have emerged as key tools for sustainable agriculture by improving crop productivity, resource-use efficiency, stress resilience, and food quality while reducing dependence on external agricultural inputs. Despite their remarkable diversity in origin and composition, increasing evidence suggests that structurally distinct biostimulants may influence overlapping conserved regulatory networks controlling plant growth and environmental adaptation. This review proposes a mechanistic convergence framework to explain how structurally distinct plant biostimulants may influence overlapping regulatory networks controlling plant growth and environmental adaptation. We examine how humic substances, seaweed extracts, protein hydrolysates, amino acids, chitosan, silicon, and microbial biostimulants regulate extracellular perception, intracellular signalling, phytohormonal crosstalk, transcriptional reprogramming, and metabolic integration, ultimately enhancing root development, nutrient and water use efficiency, photosynthesis, carbon and nitrogen metabolism, redox homeostasis, stress tolerance, crop productivity, and food quality. We further discuss how transcriptomics, proteomics, metabolomics, epigenomics, and computational biology are identifying recurring signalling and metabolic responses that may help define conserved regulatory processes and potential molecular biomarkers associated with the physiological responses induced by chemically diverse biostimulants. This systems-level framework provides a conceptual basis for the rational development of evidence-based precision biostimulants for sustainable and climate-resilient agriculture.