Developing low GI pearl millet and its potential in combating diabetes

Diabetes is a highly problematic and increasingly prevalent disease world-wide, resulting in 1.5 million deaths in 2012. Management techniques for prevention of diabetes in high-risk individuals as well as affected individuals are mainly through changes in lifestyle and dietary regulation, such as increased consumption of foods with low glycaemic index (GI). However, low GI foods may not be easily accessible especially in developing countries with a high prevalence of diabetes, such as India. The cereal crop pearl millet (Pennisetum glaucum) is one of the most abundant crops grown in India, and provides a staple food for many poor communities. Compared to other cereal crops such as wheat and maize, pearl millet is high in nutritional content (e.g. proteins, B-complex vitamins, zinc, magnesium and iron), is gluten free, and has a low GI, making it an outstanding candidate to selectively breed for lower GI for use in diabetes control diets. However, the variation in GI, and the possibility of selecting and breeding varieties with lower GI values has not yet been assessed. Using starch phenotypes (i.e. resistant starch and slowly digestible starch) as proxies for GI, the aim of this catalyst study is to assess the phenotypic and genetic variation for starch phenotypes in approx. 250 PMiGAP genotypes drawn from a global collection of pearl millet germplasm. Using next-generation genotyping-by-sequencing methods, SNP markers are being identified and genotyped across the varieties and tested for association with starch phenotypes to identify quantitative trait loci (QTL). Putative candidate genes underlying QTL which may be involved in conferring a particular starch phenotype will be identified through QTL fine-mapping and alignment of QTL-linked genomic sequences to publically available pearl millet genetic resources. Both QTL and candidate genes will be utilised in the generation of pearl millet varieties with lower GI, as a potential method to combat the increasing prevalence of global diabetes.