Flavonoid-Lignin Crosstalk: Engineering Metabolic Flux for Optimised Plant Growth and Stress Resilience

As core metabolites of the phenylpropane pathway, flavonoids and lignin compete for common metabolic flux, yet their regulatory crosstalk critically constrains resource partitioning between development and stress adaptation. In this review, we synthesise recent progress in mechanistic insights into flavonoid-mediated regulation of seed dormancy and germination, vegetative growth, and reproductive growth, while clarifying lignin's role in reinforcing cell wall biomechanical integrity and establishing hydraulic conductivity conduits. We particularly focus on multi-tiered regulatory networks through which these metabolites confer resilience to against biotic/abiotic stresses. We further establish flavonoid-lignin homoeostasis as a pivotal regulator of growth-defence trade-offs and demonstrate that its precision engineering enables synergistic enhancement of plant vigour and stress adaptation. This study provides a molecular blueprint for developing high-performance plants with balanced nutritional, stress-tolerant, and ecological traits.