Abstract
Pearl millet is an important crop for alleviating micronutrient malnutrition through genomics-assisted breeding for grain Fe (GFeC) and Zn (GZnC) content. In this study, we identified candidate genes related to iron (Fe) and zinc (Zn) metabolism through gene expression analysis and correlated it with known QTL regions for GFeC/GZnC. From a total of 114 Fe and Zn metabolism-related genes that were selected from the related crop species, we studied 29 genes. Different developmental stages exhibited tissue and stage-specific expressions for Fe and Zn metabolism genes in parents contrasting for GFeC and GZnC. Results revealed that PglZIP, PglNRAMP and PglFER gene families were candidates for GFeC and GZnC. Ferritin-like gene, PglFER1 may be the potential candidate gene for GFeC. Promoter analysis revealed Fe and Zn deficiency, hormone, metal-responsive, and salt-regulated elements. Genomic regions underlying GFeC and GZnC were validated by annotating major QTL regions for grain Fe and Zn. Interestingly, PglZIP and PglNRAMP gene families were found common with a previously reported linkage group 7 major QTL region for GFeC and GZnC. The study provides insights into the foundation for functional dissection of different Fe and Zn metabolism genes homologs and their subsequent use in pearl millet molecular breeding programs globally.
Highlights
Nutritional security is the key component to improve the health status of the world’s population as they are primarily dependent on plant-based diets
Several genes/ gene families involved in Fe and Zn homeostasis like zinc-regulated transporter (ZRT), ZIP, yellow stripe-like (YSL), natural resistance-associated macrophage protein (NRAMP), nicotianamine synthase (NAS), nicotianamine aminotransferase (NAAT), heavy metal ATPases (HMA), metal tolerant protein (MTP), zinc-induced facilitator-like (ZIFL) and others have been characterized in cereal crops
BLAST was performed against pearl millet sequences which resulted in the identification of 29 putative Fe and Zn metabolism genes
Summary
Nutritional security is the key component to improve the health status of the world’s population as they are primarily dependent on plant-based diets. A thorough understanding of the regulatory events leading to the roles and functions of Fe and Zn metabolism genes of pearl millet should help us to gain new insights into micronutrient homeostasis and mitigating malnutrition Identifying their potential in metal transport, homeostasis, and their expression levels to regulate the ions is the prime aim of such an endeavor. No genes associated with Fe and Zn metabolism genes have been characterized in P. glaucum and their transport capabilities at the time of grain filling Such findings help us in developing better lines with high grain Fe and Zn content and subsequently reducing malnutrition among resource-poor populations. An effort has been made to identify those genes that get expressed to mobilize nutrients from root to flag leaves and into developing grains in pearl millet
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