Dissecting Molecular and Biochemical Mechanisms Underlying Nutrient Acquisition and Biofortification in Sugar Beet

Root vigor is recognized as a critical determinant of sugar beet performance due to its direct influence on nutrient acquisition and overall growth. In this study, we conducted an analysis focusing on root vigor by screening diverse F2 and F3 genotypes exhibiting variable root growth phenotypes. Genotypes classified as having high or low root vigor were selected for further investigation. Using ddRAD sequencing data, we identified eight genetic variants contrasting between the high and low root vigor groups, with a particular focus on those linked to potassium acquisition pathways. These candidate variants were further validated through High-Resolution Melting and rhAmp analyses to identify variants which reliably discriminate between high and low root vigor phenotypes within segregating populations and commercial checks. Our results identified a single marker located within a gene encoding a Small Auxin-Up RNA (SAUR) family protein, which is known to be rapidly induced by auxin. SAUR proteins regulate plasma membrane H+-ATPase activity, mediating cell wall acidification and loosening, thereby promoting cell elongation and growth processes integral to root development. The findings support the role of auxin signalling in root architecture modulation and emphasize the importance of potassium transport and hormone-mediated growth regulation in biofortification efforts. The study highlights the integration of genomic technologies with physiological trait screening as a robust approach for improving agronomically important traits related to nutrient acquisition and plant vigor in sugar beet.