Maria Itria Ibba: M.IBBA@cgiar.org

Gabriel Posadas-Romano: g.posadas@CGIAR.ORG

Velu Govindan: velu@cgiar.org

Every year, millions worldwide suffer from iron (Fe) and zinc (Zn) deficiencies, leading to conditions like anemia and stunting. Biofortifying staple crops, such as wheat, is an efficient means to combat these micronutrient deficiencies. However, increasing Fe and Zn concentration in wheat grains could prove ineffective if processing methods diminish their content or bioavailability, or if antinutritional components like phytic acid (PA) hinder micronutrient absorption.

Thus, this project aimed to investigate the impact of various wheat processing methods on Fe and Zn retention and bioavailability (estimated through PA/Zn or PA/Fe molar ratio) in zinc-enriched wheat lines. Additionally, it sought to explore the genetic regulation of PA which could be an additional potential target to enhance biofortification effectiveness.

To conduct these analyses, 60 biofortified elite spring bread wheat lines were evaluated. These lines were milled at three extraction rates (70%, 85%, and 100%) and processed into chapatis and pan-bread. Monitoring Fe, Zn, PA content, and phytase activity throughout the production process revealed that milling significantly influenced Fe, Zn, and phytic acid variations. However, neither pan-bread nor chapati production adversely affected Fe and Zn concentrations. Fermentation and phytase activation in bread rendered the micronutrients more available than in chapatis with the bread obtained using 85% flour extraction rate being associated with the lowest PA/Zn (7.04) or PA/Fe (6.08) molar ratio, indicating an increased bioavailability of such micronutrients.

Overall, these findings confirm biofortification's efficacy in increasing Fe and Zn intake and underscore the importance of employing specific wheat processing techniques to maximize micronutrient consumption and bioavailability.

To better understand the genetic control of phytic acid content variation and evaluate the possibility of breeding for a reduced PA concentration, an additional set of 199 advanced spring bread wheat lines grown under both optimal conditions and reduced irrigation across two consecutive years were evaluated. Wide variation in phytic acid (ranging from 0.41 to 0.84 g/100g) was observed.

Although a strong correlation across environments could not be observed (r = 0.16 - 0.42), a strong QTL associated with significant variations in PA content in one unique environment was identified on chromosome 5BL, explaining more than 50% of the observed variation.

Further studies are required to validate the significance of this genomic region and elucidate the factors driving these changes. Nevertheless, selecting biofortified lines with reduced phytate content appears to be a promising approach to boost biofortification effectiveness.