Physiological and molecular responses of colored wheat seedlings under varying nutrient stress conditions.

Anthocyanin-rich biofortified colored wheats represent a valuable genetic resource for breeders, owing to their high antioxidant capacity, which holds great potential for developing nutrient-dense and stress-resilient cultivars. In this context, the present study investigates the physiological and molecular responses of a colored (black) wheat genotype (NABI MG-11) and a white wheat genotype (PBW 621) to individual phosphate (Pi) deficiency, iron (Fe) deficiency, and their combined stress.Our physiological, biochemical and molecular data indicates that roots and shoots of wheat seedlings exhibit a higher sensitivity to Fe deficiency compared to Pi deficiency. Under combined Pi and Fe deficiency, both the genotypes rescue sensitive root growth phenotype. However, this response was more apparent in black wheat compared to white wheat that showed lesser reduction in biomass, phosphate, iron, zinc and anthocyanin contents. Metabolome analysis suggested that more distinct anthocyanins were accumulated in black wheat under condition of dual deficiency as compared to black control and white wheat genotype, which indicates that anthocyanin accumulation was genotype-specific and stress condition dependent. Quantitative real time PCR analysis of genes responsible for anthocyanin biosynthesis, its transport and regulation showed higher expression in black wheat than white wheat under dual deficiency. Our result demonstrated that although the colored and white wheat respond in a similar pattern to changes in the rhizospheric Fe and Pi, yet black wheat showed better adaptation to deficient conditions.