From trade-off to synergy: how nutrient status modulates plant resistance to herbivorous insects?

The principle of the "growth-defense trade-off" governs how plants adjust their growth and defensive strategies in response to external factors, impacting interactions among plants, herbivorous insects, and their natural enemies. Mineral nutrients are crucial in modulating plant growth and development through their bottom-up effects. Emerging evidence has revealed complex regulatory networks that link mineral nutrients to plant defense responses, influencing the delicate balance between growth and defense against herbivores. This review aims to summarize recent advances that elucidate the impact of nutrient availability on plant defense responses. Particularly, we focus on how nutrient status shapes plant resistance to herbivores, delving into the molecular mechanisms underlying this physiological process. Moreover, the interplay between mineral nutrients and various herbivore defense mechanisms, including physical protection, plant hormone signaling, defensive metabolite production, and volatile organic compound emissions that deter herbivores or attract their natural enemies, are discussed. This comprehensive review sets the stage for future investigations into the intricate crosstalk between nutrient signaling and plant defense responses, which serves as a central mechanism to guide sustainable pest management approaches, thereby promoting balanced agroecosystem health and enhancing plant ecosystem productivity and resilience.