Iron need attention: a review on the role of iron in plants.

Plants must continuously adapt to complex dynamic environmental conditions throughout their entire life cycle. Abiotic stresses, such as drought, salinity, heavy metal toxicity, extreme temperatures significantly impair plant growth and cause substantial reductions in crop yield. Iron (Fe), an essential micronutrient, serves as a cofactor for numerous metalloenzymes and a critical component of the mitochondrial and chloroplast electron transport chains. It plays an indispensable role in fundamental physiological processes such as photosynthesis, respiration, antioxidant defense, and nitrogen metabolism. However, abiotic stress frequently disrupts iron homeostasis in plants, resulting in either iron deficiency or toxic accumulation, a dual imbalance that compromises cellular function. Such dysregulation exacerbates oxidative damage via Fenton chemistry and severely inhibits growth and development by impairing photosynthetic efficiency and enzymatic activity. Emerging evidence indicates that iron acts not merely as a nutritional element but also as a key modulator of intracellular signaling, metabolic reprogramming, and ion homeostasis, thereby contributing critically to abiotic stress resilience. This review comprehensively synthesizes current understanding of iron's regulatory roles in plant responses to major abiotic stresses, with particular emphasis on the crosstalk between iron homeostasis networks and stress activated signaling pathways. We further elucidate how perturbations in iron homeostasis exert bidirectional effects on stress tolerance, both sensitizing and, under certain contexts, potentiating adaptive responses, thereby offering conceptual and mechanistic insights to advance research on the integration of iron nutrition and stress adaptation, and to inform strategies for enhancing crop resilience.