Enhancing genetic gains and resilience to climatic stress in pearl millet

Pearl Millet grown on about 30 m ha in semi-arid ecologies of drylands in Asia and Africa is a valuable staple from humans and its stover is an important component of livestock feed in these marginal ecologies

Improvement of restorer lines for strengthening pearlmillet (Pennisetum glaucum L.) hybrid breeding in West and Central Africa

Little information was available on the genetics of pearl millet restorers available in West and Central Africa. Hence, diallel analysis was carried out using six parents and 30 F1’s, to identify the nature of gene action, and improve the restorer gene pool. The genotype ICMR 157004 is early flowering with high biomass yield. The cross ICMX 1770192 (2.19 t/ha) ICMX 1770197 (2.14 t/ha) and ICMX 1770193 (2.08 t/ha) exhibited high grain yield with early days to 50% flowering and medium plant height. Grain Fe content is positively associated with grain Zn content (r = 0.93**) but exhibited negative association with other agronomic traits indicating proper care should be taken for breeding these traits. Mean sum of squares for panicle circumference, grain yield and biomass yield exhibited significant probabilities for the maternal effects indicating the influence of maternal factors in inheritance of these traits. The estimates of narrow sense heritability for days to 50% flowering, panicle length, plant height, panicle circumference, biomass yield and grain Fe and Zn content was high indicating the predominance of additive gene action in inheritance of these traits. ICMX 1770193, ICMX 1770194, ICMX 1770197, ICMX 1770204 and ICMX 1770208 exhibited significant negative sca effects for days to 50% flowering. Positive and significant sca effects for grain Fe and Zn contents were expressed by crosses ICMX 1770197, and ICMX 1770204. Identified genotypes with good GCA and crosses with good SCA, were useful in improving the restorer lines of pearl millet to promote the hybrid pearl millet breeding in West and Central Africa

Breeding Crop Plants for Improved Human Nutrition Through Biofortification: Progress and Prospects

Micronutrients are essential minerals and vitamins required by humans in tiny amounts which play a vital role in human health and development. Over three billion people in the world are malnourished, particularly in the developing countries. Current food systems cannot provide sufficiently balanced micronutrients required to meet daily needs and to sustain the wellbeing of people in developing countries. Heavy and monotonous consumption of cereal-based foods which contain limited amounts of micronutrients is one of the major reasons for the significantly high prevalence of micronutrient deficiencies in many of the developing countries. The development of crops with enhanced micronutrient concentration is one of the most sustainable and cost-effective approaches to alleviate micronutrient malnutrition globally. In this chapter we focus on the research to improve mineral element concentration in crops through plant breeding strategies, especially in major cereal crops and a legume which are most widely cultivated and preferred in Africa and Asia. Biofortification is an appropriate strategy to increase the bioavailable concentrations of an element in edible portions of crop plants through traditional breeding practices or modern biotechnology to overcome the problem of micronutrient deficiencies. Therefore, conventional breeding with modern genetic engineering approaches are important for developing crop cultivars with enhanced micronutrient concentrations to improve human health. This chapter reports on biofortification research on rice, pearl millet, sorghum, maize, wheat and common bean

Combining ability studies of grain Fe and Zn contents of pearl millet (Pennisetum glaucum L.) in West Africa

Micronutrient malnutrition is a major challenge in Africa, where half a million children die each year because of lack of micronutrients in their food. Pearl millet is an important food and fodder crop for the people living in the Semi-Arid regions of West Africa. The present study was conducted to determine the stability, combining ability, and gene action conditions of the high level of Fe and Zn content in grain and selected agronomic traits. Hence, eight genotypes were selected based on the availability of grain Fe and Zn contents and crossed in a full diallel mating design. Progenies from an 8 × 8 diallel mating along with the parents were evaluated in an alpha lattice design with three replications in three locations for two years. The parental lines Jirani, LCIC 9702 and MORO, had positive significant general combining ability (GCA) effects for grain Fe concentration, while Jirani and MORO had positive significant GCA effects for grain Zn concentration. For the specific combining ability (SCA), among the 56 hybrids evaluated, only the hybrids LCIC 9702 × Jirani and MORO × ZANGO had positive significant SCA effects for grain Fe concentration across locations, and for grain Zn concentration, the hybrids Gamoji × MORO, LCIC 9702 × Jirani, and ICMV 167006 × Jirani had positive significant SCA effects. The reciprocal effects were significant for grain Zn concentration, grain yield, flowering time, plant height, test weight, and downy mildew incidence, suggesting that the choice of a female or male parent is critical in hybrid production. Grain Fe and Zn concentration, flowering time, plant height, panicle length, panicle girth, panicle compactness, and downy mildew incidence were found to be predominantly under additive gene action, while grain yield and test weight were predominantly under non-additive gene action. A highly positive correlation was found between grain Fe and Zn concentrations, which implies that improving grain Fe trait automatically improves the grain Zn content. The stability analysis revealed that the hybrid ICMV 167006 × Jirani was the most stable and high-yielding with a high level of grain Fe and Zn micronutrients

Implications of farmer perceived production constraints and varietal preferences to pearl millet breeding in Senegal

Pearl millet ( Pennisetum glaucum L.) plays a critical role in smallholder food security in sub-Saharan Africa. The production of pearl millet has, however, stagnated or even declined due to several factors. The objective of this study was to assess farmer perceptions on production constraints and varietal preferences in Senegal. A survey was conducted involving 150 randomly selected farmers from 15 villages, in five representative rural communities of Senegal. A semi-structured questionnaire was used, supplemented by focus group discussions. Results revealed that parasitic Striga weed was the most constraining factor to pearl millet production across the rural communes. This was followed by low soil fertility and insect pests in that order. Other constraints included lack of machinery for sowing, plant diseases, drought, seed-eating birds, limited access to land for pearl millet cultivation and limited seed availability. Among the traits for varietal preference, farmers unanimously considered grain yield as the most important trait. Other important traits mentioned were adaptation to drought, adaptation to low soil fertility and earliness. These production constraints and varietal preference should be integrated in the profile of the national pearl millet breeding programmes in order to improve the productivity and adoption of bred-cultivars.Le mil est une importante culture c\ue9r\ue9ali\ue8re et joue un r\uf4le essentiel dans la s\ue9curit\ue9 alimentaire de la plupart des producteurs de l\u2019Afrique subsaharienne. Cependant, la production est oscillante et faible en raison de plusieurs facteurs. Une \ue9tude a \ue9t\ue9 conduite pour \ue9valuer la perception des producteurs sur les contraintes limitant la production du mil et leurs pr\ue9f\ue9rences vari\ue9tales au S\ue9n\ue9gal. Une enqu\ueate avec150 producteurs s\ue9lectionn\ue9s al\ue9atoirement a \ue9t\ue9 men\ue9e dans 15 villages situ\ue9s dans cinq communaut\ue9s rurales du S\ue9n\ue9gal. Une \ue9valuation rurale participative et des enqu\ueates ont \ue9t\ue9 men\ue9es. Les r\ue9sultats ont montr\ue9 que le Striga est le facteur majeur qui limite la production de mil au niveau des diff\ue9rentes communaut\ue9s rurales. Les autres contraintes rencontr\ue9es dans les communes rurales \ue9taient le manque de machines pour le semis, les maladies, la s\ue9cheresse, les oiseaux granivores, l\u2019acc\ue8s limit\ue9 \ue0 la terre et la faible disponibilit\ue9 des semences de vari\ue9t\ue9s am\ue9lior\ue9es. Les producteurs ont unanimement consid\ue9r\ue9 le rendement en grains comme le trait le plus important dans le choix d\u2019une nouvelle vari\ue9t\ue9. Les autres traits jug\ue9s important sont l\u2019adaptation \ue0 la s\ue9cheresse l\u2019adaptation \ue0 la faible fertilit\ue9 des sols et la pr\ue9cocit\ue9. Ces contraintes de production et pr\ue9f\ue9rences vari\ue9tales doivent \ueatre incluses parmi les objectifs du programme national de s\ue9lection de mil pour am\ue9liorer la productivit\ue9 et le taux l\u2019adoption des nouvelles vari\ue9t\ue9s

Genomic diversity in pearl millet inbred lines derived from landraces and improved varieties

Background: Genetic improvement of pearl millet is lagging behind most of the major crops. Development of genomic resources is expected to expedite breeding for improved agronomic traits, stress tolerance, yield, and nutritional quality. Genotyping a breeding population with high throughput markers enables exploration of genetic diversity, population structure, and linkage disequilibrium (LD) which are important preludes for marker-trait association studies and application of genomic-assisted breeding. Results: Genotyping-by-sequencing (GBS) libraries of 309 inbred lines derived from landraces and improved varieties from Africa and India generated 54,770 high quality single nucleotide polymorphism (SNP) markers. On average one SNP per 29 Kb was mapped in the reference genome, with the telomeric regions more densely mapped than the pericentromeric regions of the chromosomes. Population structure analysis using 30,208 SNPs evenly distributed in the genome divided 309 accessions into five subpopulations with different levels of admixture. Pairwise genetic distance (GD) between accessions varied from 0.09 to 0.33 with the average distance of 0.28. Rapid LD decay implied low tendency of markers inherited together. Genetic differentiation estimates were the highest between subgroups 4 and 5, and the lowest between subgroups 1 and 2. Conclusions: Population genomic analysis of pearl millet inbred lines derived from diverse geographic and agroecological features identified five subgroups mostly following pedigree differences with different levels of admixture. It also revealed the prevalence of high genetic diversity in pearl millet, which is very useful in defining heterotic groups for hybrid breeding, trait mapping, and holds promise for improving pearl millet for yield and nutritional quality. The short LD decay observed suggests an absence of persistent haplotype blocks in pearl millet. The diverse genetic background of these lines and their low LD make this set of germplasm useful for traits mapping

Genetic variability and marker detection for rust resistance in recombinant inbred lines and backcross inbred lines of groundnut (Arachis hypogaea l.)

A F6 mapping population and backcross populations (BC1F4 and BC2F3 BC3F2) were developed from the cross between the susceptible parent GPBD-5 and resistant parents ICGV 86699 and ICGV 99005 to dissect the genetic variation and SSR markers linked to the rust resistance in groundnut. Genetic variability revealed that there were highly significant differences among recombinants for rust reaction. Less differences were observed between PCV and GCV for rust reaction in both crosses, which indicated a greater role of genetic components. High values of heritability (>80%) genetic advance and-genetic advance as percent mean was observed for rust reaction in F6 and backcross populations. Bulk segregant analysis in the segregating populations of both crosses (GPBD-5 x ICGV 86699 and GPBD-5 x ICGV 99005) indicated Tc4g10 marker was putatively linked to the rust resistant gene. The association of the putative marker identified based on DNA pooling from the selected segregants was established by single marker analysis (SMA). In the F6 population of both crosses GPBD-5 x ICGV 86699 and GPBD-5 x ICGV 99005, the Tc4glO marker accounted for 72.40% and 50.60% total variation, respectively. Tc4g10 marker accounted for 67.10%,38.40% and 61.30% total variation in the cross GPBD-5 x ICGV 86699, and the same marker accounted for 73.8%, 54.7% and 84.4% total variation in the cross GPBD-5 x ICGV 99005 in BC1F4, BC2F3 and BC3F2, respectively. This marker can be used in marker assisted selection for rust resistance in groundnut improvement programs

Backcross breeding in groundnut (Arachis hypogaea L.)

Rust caused by Puccinia arachidis Speg. is the most serious disease of groundnut and causes substantial yield loss and reduces the fodder and seed quality. Recombinant inbred lines (F6) were generated by SSD method from cross GPBD-5 x GPBD-4 and the rust resistant plants were backcrossed to the recurrent parent (GPBD-5) to develop a backcross population (BC1F4). The objective ofthis experiment was to study the possibilities of linkage break-down between yield component traits and rust resistance in groundnut. Analysis of data revealed that there was a shift in correlation from negative (F6) to positive significant direction (BC1F4) between pod yield per plant with plant height and between plant height with number of primary branches. Similarly there was linkage break-down between negative significant to positive significant association of number of primary branches with number of pods per plant, kernel yield per plant and shelling percent at both genotypic and phenotypic levels. Altogether a desirable shift in association and the proof of broken repulsion phase linkage and release of concealed variability, which is useful in plant breeding, provides a lot of scope for selection. Unchanged negative association between pod yield per plant with reaction to rust and shelling percent in both phenotypic and genotypic level in both the populations, indicated the operation of strong linkage blocks and which requires an intensive selection to combine disease resistance with yield. Otherwise inter-mating of highly extreme segregants in the populations also would cause breakage of these stubborn linkages. Thus, for yield component traits, backcrossing of selected plants is more rewarding than the single cross and advance by single seed decent method of breeding in groundnut

Marker detection and genetic analysis for rust resistance of recombinant and backcross inbred lines in groundnut (Arachis hypogaea L.)

The present work was conducted to study the genetic variation and identification of microsatellite markers linked to rust resistance in groundnut. An F6 mapping population and three backcross populations (BC1F4, BC2F3 and BC3F2) were developed from a cross between the susceptible parent GPBD-5 and resistant parent GPBD-4. There were highly significant differences among recombinants for reaction to rust. A little difference was observed between PCV and GCV for reaction to rust. High heritability coupled with high genetic advance as per cent of mean was observed for reaction to rust in F6, and backcross populations. Bulk segregant analysis in the segregating population of GPBD-5 x GPBD-4 indicated TC5A06 to be putatively linked to rust resistance i.e., single marker analysis (SMA). This marker can be used in marker assisted selection for rust resistance in groundnut improvement program

Optimizing speed breeding and seed/ pod chip based genotyping techniques in pigeonpea: A way forward for high throughput line development

Background: The challenge of pigeonpea breeding lies in its photosensitivity and seasonal specificity. This poses a problem to the breeder, as it restricts to single generation advancement in a year. Currently, the cross to cultivar gap is twelve to thirteen years resulting in a limited number of varietal releases over the past six decades. Shortening the breeding cycle was need of the hour, unlikely achieved by conventional breeding. To overcome these hindrances speed breeding was a necessary leap. An experiment was planned to optimize the speed breeding coupled with single seed descent and seed or pod chip-based genotyping to shorten the breeding cycle in pigeonpea at ICRISAT, Hyderabad. Monitored photoperiod, light wavelength, temperature and crop management regime were the indicators attributing to the success of speed breeding. Result A photoperiod of 13 h: 8 h: 13 h at vegetative: flowering and pod filling stages is ideal for shortening the breeding cycle. Broad spectrum light (5700 K LED) hastened early vegetative growth and pod formation. Whereas farred (735 nm) light favoured early flowering. A significant difference between the photoperiods, genotypes as well as photoperiod x genotype interaction for both days to flowering and plant height was noted. Conclusion The optimized protocol serves as a road map for rapid generation advancement in pigeonpea. Deploying this protocol, it is possible to advance 2–4 generations per year. The breeding cycle can be reduced to 2–4 years which otherwise takes 7 years under conventional breeding. Single Seed Descent and seed or pod chip-based genotyping for early generation marker assisted selection, strengthened the precision of this technique aiding in high throughput line development