Breeding Drought-Tolerant Pearl Millet using conventional and genomic approaches: Achievements and prospects

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a C4 crop cultivated for its grain and stover in crop-livestock-based rain-fed farming systems of tropics and subtropics in the Indian subcontinent and sub-Saharan Africa. The intensity of drought is predicted to further exacerbate because of looming climate change, necessitating greater focus on pearl millet breeding for drought tolerance. The nature of drought in different target populations of pearl millet-growing environments (TPEs) is highly variable in its timing, intensity, and duration. Pearl millet response to drought in various growth stages has been studied comprehensively. Dissection of drought tolerance physiology and phenology has helped in understanding the yield formation process under drought conditions. The overall understanding of TPEs and differential sensitivity of various growth stages to water stress helped to identify target traits for manipulation through breeding for drought tolerance. Recent advancement in high-throughput phenotyping platforms has made it more realistic to screen large populations/germplasm for drought-adaptive traits. The role of adapted germplasm has been emphasized for drought breeding, as the measured performance under drought stress is largely an outcome of adaptation to stress environments. Hybridization of adapted landraces with selected elite genetic material has been stated to amalgamate adaptation and productivity. Substantial progress has been made in the development of genomic resources that have been used to explore genetic diversity, linkage mapping (QTLs), marker-trait association (MTA), and genomic selection (GS) in pearl millet. High-throughput genotyping (HTPG) platforms are now available at a low cost, offering enormous opportunities to apply markers assisted selection (MAS) in conventional breeding programs targeting drought tolerance. Next-generation sequencing (NGS) technology, micro-environmental modeling, and pearl millet whole genome re-sequence information covering circa 1,000 wild and cultivated accessions have helped to greater understand germplasm, genomes, candidate genes, and markers. Their application in molecular breeding would lead to the development of high-yielding and drought-tolerant pearl millet cultivars. This review examines how the strategic use of genetic resources, modern genomics, molecular biology, and shuttle breeding can further enhance the development and delivery of drought-tolerant cultivars

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Not AvailableGenetic and functional diversity of osmotolerant bacterial endophytes colonizing the root, stem, and leaf tissues of pearl millet genotypes differing in their drought susceptibility was assessed. Two genotypes of pearl millet, viz., the drought tolerant genotype TT-1 and the drought susceptible genotype PPMI-69, were used in the present study. Diazotrophs were found to be the predominant colonizers, followed by the Gram positive bacteria in most of the tissues of both the genotypes. Higher proportion of bacterial endophytes obtained from the drought tolerant genotype was found to be osmotolerant. Results of 16S rRNA gene-ARDRA analysis grouped 50 of the highly osmotolerant isolates into 16 clusters, out of which nine clusters had only one isolate each, indicating their uniqueness.One cluster had 21 isolates and remaining clusters were represented by isolates ranging fromtwo to four. The representative isolates from each cluster were identified, and Bacillus was found to be the most prevalent osmotolerant genera with many different species. Other endophytic bacteria belonged to Pseudomonas sp., Stenotrophomonas sp., and Macrococcus caseolyticus. High phylogenetic diversity was observed in the roots of the drought tolerant genotype while different tissues of the drought susceptible genotype showed less diversity. Isolates of Bacillus axarquiensis were present in all the tissues of both the genotypes of pearl millet. However, most of the other endophytic bacteria showed tissue/genotype specificity. With the exception of B. axarquiensis and B. thuringiensis, rest all the species of Bacillus were found colonizing only the drought-tolerant genotype; while M. caseolyticus colonized all the tissues of only the drought susceptible genotype. There was high incidence of IAA producers and low incidence of ACC deaminase producers among the isolates from the root tissues of the drought-tolerant genotype while reverse was the case for the drought-susceptible genotype. Thus, host played an important role in the selection of endophytes based on both phylogenetic and functional traits.Not Availabl

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Not AvailablePearl millet can be viably used for food diversification due to its balanced nutritional composition. Nutritional parameters are conventionally assessed using labour and time-intensive strenuous conventional methods for germplasm screening. Near-infrared reflectance spectroscopy (NIRS) uses near-infrared sections of the electro magnetic spectrum for precise and speedy determination of biochemical parameters for large germplasm. MPLS (Modified Partial Least Squares) regression based NIRS prediction models were developed to assess starch, resistant starch, amylose, protein, oil, total dietary fibre, phenolics, total soluble sugars, phytic acid for high throughput screening of pearl millet germplasm. Mathematical treatments executed by permutation and com binations for calibrating the model, where 2nd, 3rd, and 4th derivatives produced the best results. Treatments “4,5,4,1” was finalized for protein, oil, resistant starch, total dietary fibre, “3,4,4,1” for phenolics, “2,8,4,1” for amylose, “2,4,4,1” for phytic acid, “4,7,4,1” for total soluble sugars and “2,8,4,1” for starch. Treatments with the highest 1-Variance ratio, RSQinternal (coefficient of determination) values, lowest SEC(V) (standard error of cross validation), SEP(C) (standard error of performance) were identified for subsequent validation. External valida tion determined the prediction accuracy based on RSQexternal, RPD (residual prediction deviation), SD (standard deviation), p-value ≥ 0.05 and low SEP(C).The present work is funded by Division of Agricultural Education, ICAR under the Niche Area of Excellence (NAE) Programme (Scheme Strengthening and Development of Higher Agricultural Education in India) (Project Sanction no. Edn. 5(22)/2017-EP&HS, 2019; IARI code: 12/223) and the support of the Global Environment Facility (GEF) of the United Nations Environment Program (UNEP) within the project “Mainstreaming agricultural biodiversity conservation and utilization in the agricultural sector to ensure ecosystem services and reduce vulnerability”

In-Silico elucidation of the three-dimensional molecular structures defining the resistance mechanism by NBS-LRR proteins towards foliar blast disease elicitins in pearl millet

Abstract: Foliar blast disease caused by the fungus Magnaporthe grisea (Hebert) Barr, forms one of the worst scourge for pearl millet recently. Resistant lines recognizes molecular signature of pathogen infection (Avr gene products) and triggers downstream response signaling pathways in host plants through activation of Resistance (R) proteins, that works as a molecular switch for pathogen defence signalling and represent one of the largest plant gene family. Hence, understanding molecular structure and function of R proteins has been of paramount importance for plant biologists. The present study aimed at predicting three-dimensional structure of Resistance gene candidate (RGCs) protein RGPM 213 through ab-initio method of protein modeling. The structured protein models were further validated for structure and function and determine the ADP ligand binding site on the molecule through bioinformatics software. Availability of 3D structural model for NBS and other domains in RGCs will help in getting deeper insight in these pathogen defense genes, thereby manipulating them by site directed mutation or protein engineering to increase its efficacy towards the fight against pearl millet blast and other pathogens. Conference Details: 1st National Genetic Congress on Genetics for Sustainable Food, Health and Nutrition Security. ICAR-Indian Agricultural Research Institute, New Delhi.   Publication date: 2018/12/14 </p