Biofortifying the Common Bean-Interplay of Iron, Zinc and Phytic Acid: A Review

Common bean is a vital basic food and vegetable legume crop cultivated worldwide. Despite its nutritional importance, more than a third of humanity is affected by deficiencies in important micronutrients like iron (Fe) and zinc (Zn). A primary barrier to improving the nutritional content of common bean is the presence of phytic acid (PA), the principal phosphorus reservoir in legumes, which significantly reduces the bioavailability of these essential minerals. However, the interaction among Fe, Zn and PA in common bean remains poorly understood. This review focuses on the complex interplay among Fe, Zn and PA in common bean and this interaction’s combined implications for sustainable agriculture and human nutrition. Recent advances in phenotyping approaches have transformed more precise quantification of Fe, Zn and PA content across diverse bean genotypes, paving the way for effective selection and breeding strategies. Building on these phenotyping tools, this review explores the substantial genetic variation in mineral and PA content, as well as the molecular mechanisms regulating their accumulation and transport. PA significantly impedes mineral absorption, underscoring the importance of breeding efforts that aim to enhance Fe and Zn concentrations while simultaneously reducing PA levels. Molecular biology developments, such as genome-wide association studies (GWAS) and transcriptomic analysis, have enabled researchers to pinpoint crucial genes and quantitative trait loci (QTL) linked to these characteristics. Furthermore, the review addresses current challenges and future directions for developing biofortified common bean varieties, considering both genetic and environmental influences.