Abstract
Pearl millet is a climate-resilient, drought-tolerant crop capable of growing in marginal environments of arid and semi-arid regions globally. Pearl millet is a staple food for more than 90 million people living in poverty and can address the triple burden of malnutrition substantially. It remained a neglected crop until the turn of the 21st century, and much emphasis has been placed since then on the development of various genetic and genomic resources for whole-genome scan studies, such as the genome-wide association studies (GWAS) and genomic selection (GS). This was facilitated by the advent of sequencing-based genotyping, such as genotyping-by-sequencing (GBS), RAD-sequencing, and whole-genome re-sequencing (WGRS) in pearl millet. To carry out GWAS and GS, a world association mapping panel called the Pearl Millet inbred Germplasm Association Panel (PMiGAP) was developed at ICRISAT in partnership with Aberystwyth University. This panel consisted of germplasm lines, landraces, and breeding lines from 27 countries and was re-sequenced using the WGRS approach. It has a repository of circa 29 million genome-wide SNPs. PMiGAP has been used to map traits related to drought tolerance, grain Fe and Zn content, nitrogen use efficiency, components of endosperm starch, grain yield, etc. Genomic selection in pearl millet was jump-started recently by WGRS, RAD, and tGBS (tunable genotyping-by-sequencing) approaches for the PMiGAP and hybrid parental lines. Using multi-environment phenotyping of various training populations, initial attempts have been made to develop genomic selection models. This mini review discusses advances and prospects in GWAS and GS for pearl millet.
Highlights
INTRODUCTIONOver the last five years, significant work has been carried out on pearl millet related association mapping (AM) studies, and this gives information about genetic diversity and linkage disequilibrium (LD)
We review the advances made in the development of genetic and genomic resources for their use in genome-wide association studies (GWAS) and genomic selection (GS) in pearl millet
QTLmapping/interval mapping (IM) can be done by developing various mapping populations viz., F2, and recombinant inbred line (RIL), nearisogenic line (NIL), back cross (BC), and doubled haploid (DH)derived populations in which one can assume a clear cut degree of relatedness for the recombination events between the two contrasting parents for the trait of interest (Abdurakhmonov and Abdukarimov, 2008)
Summary
Over the last five years, significant work has been carried out on pearl millet related AM studies, and this gives information about genetic diversity and linkage disequilibrium (LD) To get over this problem, ICRISAT, in association with AU, developed a world association mapping panel called the Pearl Millet inbred Germplasm Association Panel (PMiGAP). A subset of 21 polymorphic EST-SSRs and 6 genomic SSR markers were developed using sequence information from 3,520 expressed sequence tags (ESTs) and used in genome mapping of different pearl millet mapping populations (Senthilvel et al, 2008) These potentially developed EST-SSRs were deployed in marker-aided breeding for yield and drought stress resistance in pearl millet at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). Senegalese landraces, with genotyping by sequencing (GBS) of PstI-MspI reduced representation libraries
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