Abstract
Iron (Fe) deficiency is a major constraint to wheat productivity in calcareous soils, necessitating the identification of cultivars with improved Fe-use efficiency. This study compared two Turkish bread wheat cultivars, Destan and Reis, under Fe-deficient (2 µM) and Fe-sufficient (50 µM) conditions to elucidate morphological, physiological, anatomical, ionomic, and molecular responses associated with Fe efficiency. Although Destan exhibited higher baseline growth under Fe sufficiency, its response to Fe limitation was characterized by a smaller reduction in several physiological and growth-related traits relative to Reis. Under Fe deficiency, Destan maintained higher chlorophyll content, biomass, root system development, and shoot Fe concentration than Reis. Ionomic analysis revealed coordinated enrichment of Fe along with Zn, Cu, Ni, K, and Ca in Destan, whereas Reis showed disrupted mineral homeostasis. Anatomical observations demonstrated enhanced root hair formation, preserved endodermis thickness, and distinct vascular organization in Destan under Fe deficiency, suggesting improved internal transport regulation. At the molecular level, Destan showed strong induction of Strategy II iron acquisition genes, including Zinc-Induced Facilitator-Like 4 ( TaZIFL4 ), Nicotianamine Synthase 3 ( TaNAS3 ), and Nicotianamine Aminotransferase 1 ( TaNAAT1 ), whereas Reis exhibited weaker activation of these pathways. Bromocresol purple assays indicated limited rhizosphere acidification in Destan, consistent with a Strategy II-dominant Fe uptake mechanism in wheat. However, Destan exhibited a greater proportional decline in grain yield under Fe-deficient conditions compared with Reis, indicating lower yield stability despite its stronger physiological and molecular responses. Collectively, these results indicate that Destan displays a more integrated and efficient Strategy II-based response to low Fe availability, highlighting its potential for improving Fe acquisition mechanisms, although yield stability under Fe deficiency requires further consideration.