Genetic and Genomic Resources of Small Millets

Abstract

Small millets are very promising agricultural entity to ensure global food security. They gained remarkable importance in agriculture due to their resilience to climatic changes and increasing demand for nutritious food and feed. The genetic variability in the core and mini-core germplasm of small millets was characterized for nutritional composition and capacity to tolerate abiotic stresses that can be infused in breeding programs. Other than the foxtail millet, availability of genomic information in small millets is far below the mark for use in marker-assisted breeding and other genetic improvement programs. The genome sequence of foxtail millet has recently triggered a plethora of post-genomic analysis and envisaged foxtail millet as a model organism for the C 4 grasses and bioenergy research. Recent developments in the next-generation sequencing technologies enabled us, with the simultaneous discovery of high-throughput markers and multiplexed genotyping of germplasm, to speedup markerassisted breeding. In this context, an in-depth analysis of the wealth of diverse germplasm resources and future perspectives of integrating genomics in genome-wide marker-trait association and breeding in small millets is worthy. ABBREVIATIONS cDNA D complementary DNA cM D centimorgan DREB D dehydration response element binding FAO D Food and Agricultural Organization ICAR D Indian Council of Agricultural Research ICRISAT D International Crops Research Institute for the Semi-Arid Tropics Mb D mega basepairs Mha D million hectares Mt D million tonnes Mya D million years ago NARS D National Agricultural Research System NCBI D National Center for Biotechnology Information NGS D next-generation sequencing PCR D polymerase chain reaction PGR D plant genetic resources SNP D single nucleotide polymorphism SSR D simple sequence repeat QTLs D quantitative trait loci

Proso Millet (Panicum miliaceum L.) and Its Potential for Cultivation in the Pacific Northwest, U.S.: A Review

“…Genetic improvement through plant breeding requires effective utilization of diverse germplasm (Kole et al, 2015; Saha et al, 2016), identification and evaluation of core and mini-core collections (Salini et al, 2010; Upadhyaya et al, 2010, 2011; Goron and Raizada, 2015) and accurate phenotyping systems (Lata, 2015). Some traits which can be selected for under PNW growing conditions may include drought tolerance which can influence harvest-index, yield, and water use efficiency (Seghatoleslami et al, 2008); fermentation efficiency (Rose and Santra, 2013); and yield under abiotic and biotic stresses such as low input, salinity, drought, pests, and diseases (Goron and Raizada, 2015).…”

“…However, in relation to its abundant morphological variations, the genetic diversity of proso millet has not yet been adequately assessed (Trivedi et al, 2015; Liu et al, 2016). As in other millets, there are no mutants or mutant populations in proso millet to study gene functions through reverse genetics (Saha et al, 2016); the waxy mutants are natural variants of the waxy gene (Hunt et al, 2010). Previously, inadequate molecular markers combined with the challenges of a tetraploid genome such as inconsistent meiotic processes, allelic and non-allelic combinations, and poor correlation between genotype and phenotype (Saha et al, 2016) have made it difficult to conduct genetic and genomic studies in proso millet.…”

“…As in other millets, there are no mutants or mutant populations in proso millet to study gene functions through reverse genetics (Saha et al, 2016); the waxy mutants are natural variants of the waxy gene (Hunt et al, 2010). Previously, inadequate molecular markers combined with the challenges of a tetraploid genome such as inconsistent meiotic processes, allelic and non-allelic combinations, and poor correlation between genotype and phenotype (Saha et al, 2016) have made it difficult to conduct genetic and genomic studies in proso millet. However, with the discovery of SNPs by GBS (Rajput et al, 2016) and the identification of differentially expressed genes and thousands of SSR and SNP loci by transcriptome analysis (Yue et al, 2016a,b), a considerable number of molecular markers are currently available for genomic research in proso millet.…”

Setaria viridis as a Model System to Advance Millet Genetics and Genomics

“…Generally, millets are some of the most well-adapted crops to drought, heat, and low nutrient input conditions (Dwivedi et al, 2011; Goron and Raizada, 2015; Saha et al, 2016). Given the increasing global population and decreasing arable lands, the stress tolerant millets are ideal candidates for crop production in climates that are not suitable for major crops.…”

“…This is especially important for millet-growing developing countries in Asia and Africa. However, common features of millets, including complex polyploid genomes, large plant stature, and long generation times ( Table 1 ) hinder both breeding and genetic research (Goron and Raizada, 2015; Saha et al, 2016). …”