Molecular mechanisms of wheat acclimation to soil degradation: Insights into salt stress, heavy metal contamination, and nutrient deficiency

Abstract

Wheat is the world’s second-largest crop, feeding over 30 % of the global population. To meet increasing food demand, substantial amounts of fertilizers have been used to boost yields. However, excessive fertilization has led to severe soil degradation, including salinization, heavy metal contamination, and nutrient depletion, which negatively impact wheat yield and quality over time. This review highlights recent advances in understanding wheat acclimation thresholds and the molecular mechanisms involved in responding to adverse soil environments. Key molecular responses include: (1) enhanced antioxidant enzyme activity and the accumulation of protective compounds that mitigate reactive oxygen species and stabilize cellular structures; (2) activation of transporter and ion channel-related genes to promote Na⁺ efflux and reduce salt toxicity; (3) coordinated action of chelation and transport genes that bind, compartmentalize, and expel toxic metal ions, thereby reducing heavy metal toxicity; and (4) upregulation of root architecture and high-affinity nutrient transporter genes to improve nutrient acquisition under deficiency stress. Acclimation thresholds to salinity, heavy metals, and nutrient limitations vary among wheat varieties due to underlying genetic differences. Understanding plant responses to combined soil stresses and leveraging these traits through advanced breeding strategies will be key to developing resilient varieties for sustainable agriculture.