Genetic dissection of minerals and phytate content in pearl millet germplasm panel using genome-wide association study

Abstract

Billions of people around the world suffer from malnutrition, leading to severe adverse health effects. Pearl millet (Pennisetum glaucum) is a multifaceted versatile crop with excellent nutritional profile which can help to combat nutritional disorders and climate change. In this study, we evaluated the global pearl millet germplasm panel known as PMiGAP for natural variation and genetic maker trait associations for important minerals, that is, iron, zinc, calcium, magnesium, potassium and sodium along with phytate. The genotypes IP-15947, IP-5121, IP-4020, IP-12768, IP-5695, IP-8786 and IP-11310 were found to be superior for majority of minerals examined but had lower phytate-to-zinc ratio. Phytate/mineral molar ratios are typically used to predict the bioavailability of iron and calcium contents in grains, and surprisingly none of the PMiGAP genotypes showed such ratios below threshold indicating PMiGAP entries studied in this study seriously suffer from bioavailability issues of these minerals. On the other hand, 73 genotypes had lower zinc/phytate ratio than the threshold in the germplasm panel. Iron and zinc content had significant positive association among them but phytate content in general was not significantly correlated with minerals except for magnesium and potassium. A genome-wide association study using 456 K SNPs identified 74 significant marker–trait associations and 59 candidate genes around 50 Kb distance near the significant SNPs. Ten significant SNPs were found within the candidate genes. The associated markers and the candidate genes provide new insights into the genetic architecture of the mineral traits studied and will facilitate marker-assisted selection to accelerate breeding of such minerals in future varieties to combat rising malnutrition problem via diet.