Reframing sorghum biofortification: multi-trait nutritional dissection of Sudanese wild germplasm reveals...

Sorghum is a cornerstone of food security in Sudan, yet sorghum-based diets contribute to widespread micronutrient deficiencies. Conventional biofortification has focused on raising grain mineral concentrations, overlooking the antinutrients and matrix factors that govern actual nutrient absorption. We hypothesized that Sudanese wild sorghum, encompassing a deeper allelic pool than cultivated lines, harbors decoupled variation in mineral density, extractability, and protein quality that could redirect breeding toward functional nutritional outcomes.

A panel of 70 wild accessions, representing six taxa collected across diverse Sudanese agro-ecologies, was advanced through three single-seed-descent cycles and evaluated in a replicated alpha-lattice trial for total and HCl-extractable Fe and Zn, phytate, and soluble protein.

Substantial variation was detected across traits, with total Fe ranging from 2.65 to 8.20 mg/100 g and Fe extractability reaching 44.12%, often in genotypes with modest total Fe levels. Total Zn (0.25-0.81 mg/100 g) and Zn extractability (up to 57.37%) likewise showed independent distributions, while phytate (210.37-380.21 mg/100 g) varied largely independently of HCl-extractable Fe. Principal component analysis explained 55.4% of the variance and separated mineral accumulation, extractability, and protein functionality into orthogonal trait domains. High broad-sense heritability (0.83-0.99) and substantial genetic advance (GAM up to 54.19%) indicated strong selection potential. Elite accessions, notably HSD14541 and HSD14468, combined low phytate with high mineral extractability and protein solubility. These findings establish wild Sudanese sorghum as a strategic genetic resource and reposition in vitro mineral accessibility (estimated as HCl-extractability), rather than concentration alone, as a breeding target.