Micronutrient malnutrition, especially deficiency of two mineral elements, iron [Fe] and zinc [Zn] in the developing world needs urgent attention. Pearl millet is one of the best crops with many nutritional properties and is accessible to the poor. We report findings of the first attempt to mine favorable alleles for grain iron and zinc content through association mapping in pearl millet. An association mapping panel of 130 diverse lines was evaluated at Delhi, Jodhpur and Dharwad, representing all the three pearl millet growing agro-climatic zones of India, during 2014 and 2015. Wide range of variation was observed for grain iron (32.3–111.9 ppm) and zinc (26.6–73.7 ppm) content. Genotyping with 114 representative polymorphic SSRs revealed 0.35 mean gene diversity. STRUCTURE analysis revealed presence of three sub-populations which was further supported by Neighbor-Joining method of clustering and principal coordinate analysis (PCoA). Marker-trait associations (MTAs) were analyzed with 267 markers (250 SSRs and 17 genic markers) in both general linear model (GLM) and mixed linear model (MLM), however, MTAs resulting from MLM were considered for more robustness of the associations. After appropriate Bonferroni correction, Xpsmp 2261 (13.34% R2-value), Xipes 0180 (R2-value of 11.40%) and Xipes 0096 (R2-value of 11.38%) were consistently associated with grain iron and zinc content for all the three locations. Favorable alleles and promising lines were identified for across and specific environments. PPMI 1102 had highest number (7) of favorable alleles, followed by four each for PPMFeZMP 199 and PPMI 708 for across the environment performance for both grain Fe and Zn content, while PPMI 1104 had alleles specific to Dharwad for grain Fe and Zn content. When compared with the reference genome Tift 23D2B1-P1-P5, Xpsmp 2261 amplicon was identified in intergenic region on pseudomolecule 5, while the other marker, Xipes 0810 was observed to be overlapping with aspartic proteinase (Asp) gene on pseudomolecule 3. Thus, this study can help in breeding new lines with enhanced micronutrient content using marker-assisted selection (MAS) in pearl millet leading to improved well-being especially for women and children.
Intergeneric hybridization between wheat (Triticum aestivum L.) and a wild weedy species, Imperata cylindrica (2n ¼ 20) resulted in the recovery of a high frequency of wheat haploids, which were obtained through the elimination of I. cylindrica chromosomes. Cytological analysis of the root tips revealed the somatic chromosome count of the regenerants equalled 21. Haploid regenerants were also obtained in all the crosses of wheat F 1 s with I. cylindrica, implying the genotype nonspecific nature of wheat · I. cylindrica hybridization. Variation among wheat F 1 hybrids was observed with respect to seed formation (44.9-84.5%), embryo formation (15.1-47.7%) and regeneration (27.0-75.0%) in crosses with I. cylindrica. Comparisons based on the efficiency of I. cylindrica and maize (Zea mays) as pollen sources indicated that Imperata-mediated haploid production is equally efficient. There is natural coincidence of flowering period of I. cylindrica with that of wheat under sub-temperate conditions which is advantageous compared with maize, which cannot be grown during the winter season in the sub-temperate regions.
Micronutrient malnutrition, especially the paucity of iron (Fe) and zinc (Zn) is posing a big threat to the world affecting nearly 25% of worldwide population. Pearl millet is endowed with huge amount of variability for micronutrients especially for grain Fe and Zn content. Micronutrient enrichment in pearl millet is possible by identifying stable genotypes for high levels of micronutrients and utilising them in breeding programme. In this context, a set of 40 pearl millet genotypes along with one check, Dhanshakti (G30), were evaluated at three different agro climatic zones during the year 2014 for grain iron (Fe) and zinc (Zn) contents using Atomic Absorption Spectrometry. The genotypes contributed 58.3% and 52.8% of the total variation for grain Fe and Zn content, respectively. The magnitude of variation contributed by interaction component was also relatively high (39.7% and 32.5% for grain Fe and Zn). Both AMMI and GGE biplot analysis identified desirable genotypes; PPMI 708 (G40), PPMI 1102 (G25) and PPMI 683 (G39) for grain Fe content, whereas PPMI 708 (G40), PPMI 1116 (G24) and PPMI 683 (G39) for grain Zn content. The Pearson correlation coefficient for grain Fe and Zn content showed that both traits are highly associated (r = 0.8, p <0.01) and these traits did not associate significantly with grain yield. Hence, there is possibility for simultaneous improvement of both grain Fe and Zn content without compromising for grain yield.
Biofortification of lines of pearl millet (Pennisetum glaucum (L.) R.Br.) with increased iron (Fe) and zinc (Zn) will have great impact because pearl millet is an indispensable component of food and nutritional security of inhabitants of arid and semi-arid regions. The aim of the present study was to assess the stability of Fe and Zn content in recombinant inbred lines (RILs) developed for grain Fe and Zn content, and to use these lines in developing micronutrient-rich pearl millet hybrids. A mapping population consisting of 210 RILs along, with parents and checks, was assessed in three consecutive years (2014–16) under rainfed conditions at the same experimental location in an alpha design with two repetitions. Significant differences were observed in genotype, environment and genotype × environment interaction mean squares for all variables, particularly grain micronutrients. The first two principal components of an interaction principal component analysis cumulatively explained 100% of the total variation; respective contributions of the first and second components were 64.0% and 36.0% for Fe, and 58.1% and 41.9% for Zn. A positive and moderately high correlation (0.696**) between Fe and Zn contents suggests good prospects of simultaneous improvement for both micronutrients. Among the 210 RILs, RIL 69, RIL 186, RIL 191, RIL 149 and RIL 45 were found to be more stable with higher mean micronutrient content, additive main effects and multiplicative interaction stability value (ASV) and genotype selection index (GSI) under rainfed condition. These RILs are promising and can be tested further for their combining ability for yield as well as grain micronutrient content for developing superior biofortified, heterotic pearl millet hybrids.
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