Mahalingam Govindaraj

Genetic architecture of open-pollinated varieties of pearl millet for grain iron and zinc densities

Genetic architecture of two commercial open-pollinated varieties of pearl millet (ICTP 8203 and ICMV 221) for grain iron and zinc densities was studied using 160 full-sib progenies each that were developed following North Carolina Design -1 and evaluated for two seasons. Results showed predominantly additive genetic variance and nonsignificant additive gene effect × environment interaction variance compared to large and significant dominance × environment interaction variance for both micronutrients in both populations. This translated into high narrow-sense heritability for Fe (65%) and Zn (86%) in ICTP 8203, and moderate heritability of 45% for both micronutrients in ICMV 221. In comparison, 1000-seed weight, generally assumed to be highly heritable, was predominantly under dominance gene control and had large dominance × environment interaction, giving the narrow-sense heritability estimates of 31% in ICTP 8203 and 13% in ICMV 221. These results, and highly significant and positive correlation observed between Fe and Zn densities, and non-significant correlations of these micronutrients with grain weight suggest that simultaneous selection for Fe and Zn densities in these populations can be effectively made without compromising the grain size.

Inheritance of fertility restoration of A5 cytoplasmic-nuclear male sterility system in pearl millet [Pennisetum glaucum (L.) R. Br.]

The A5 cytoplasmic-nuclear male sterility (CMS), the most stable cytoplasm available in pearl millet [Pennisetum glaucum (L). R. Br.] is yet to be utilized on large scale by breeders owing to limited fertility restoration in the available germplasm for this cytoplasm. An understanding of the inheritance of fertility restoration can make significant contributions to restorer breeding efficiency of this CMS system. This study investigated inheritance of fertility restoration of this CMS system in which three diverse isonuclear A-lines (P1) were crossed with two A5 restorer lines (P2) to produce 4 F1s and their respective F2s and two backcrosses. These were evaluated for male sterility (S) and fertility (F) for two seasons at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Patancheru. The segregation patterns in the F2 (54F:10S) and BCP1 (3F:1S) were broadly suggestive of trigenic inheritance of male fertility restoration, where dominant alleles at any two of the three duplicate complimentary loci will lead to fertility restoration.

Effect of grain colour on iron and zinc density in pearl millet

Pearl millet (Pennisetum glaucum (L.) R. Br.) is a climate resilient crop with higher nutrition and serve as staple food for several million populations in semi-arid regions of India and Africa. To utilize the nutritional variability of this crop, biofortification research has been initiated to combat micronutrient malnutrition, chiefly iron (Fe) and zinc (Zn) deficiency. Large variability for grain Fe and Zn density has been reported in pearl millet and mostly the high-Fe lines had relatively dark grey grain colour. Therefore, this study was designed to investigate the effect of grain colour on grain Fe and Zn density in pearl millet. Two dark grey lines were crossed with five white grain colour lines to produce 10 hybrids. These hybrids were evaluated along with their parental lines for Fe and Zn density in two seasons. Highly significant Fe density differences observed for both parents and hybrids while significant Zn density differences observed only for hybrids. The significant genotype × environment (G × E) interaction observed for Fe and Zn density in hybrid trial. Interestingly, grain colour× environment variance was not significant for both micronutrients. Results indicate both micronutrients were not differed from white to grey grain lots among hybrids (70-103 mg kg-1 Fe density and 64-80 mg kg-1Zn density), implying the genetic improvement of grain Fe and Zn density in pearl millet is highly feasible without compromising the grain colour preference of the farmers and consumers. Further, highly positive and significant correlation between these two micronutrient density irrespective of the grain colour recommended increase in Zn density as an associated trait while breeding for high Fe density in pearl millet.

Allelic relationship between restorer genes for A1 and A4 CMS systems in pearl millet

Understanding the allelic complementation of restoration among the stable restorer lines will contribute to robust pearl millet restorer breeding program. Thus, present study aimed to test allelic relationship between four diverse restorer lines each for A1 and A4 cytoplasmic male sterility (CMS) systems to find linkage between restorer genes carried by different restorers of each CMS systems. Six testcrosses were developed for each CMS system by crossing each of A1 and A4 male sterile lines (81A1 and 81 A4) with all possible combination of F1s among four A1 restorers and A4 restorers, respectively. Almost all the plants in these testcrosses showed complete male fertility indicating presence of same fertility restoration gene (allelic) is present in all the four restorer lines of A1 CMS system. Similar results were found for A4 CMS system. This single gene system within A1 and A4 provides the opportunity to breeders to incorporate this allelic restorer gene into any of the advanced lines for its rapid conversion into new restorer lines besides to search for new restorer gene for future diversification.

Energy-dispersive X-ray fluorescence spectrometry for cost-Effective and rapid screening of pearl millet germplasm and breeding lines for grain Iron and Zinc density

ABSTRACT Comparison of energy-dispersive X-ray fluorescence (XRF) and inductively coupled plasma-optical emission spectroscopy (ICP) for iron (Fe) and zinc (Zn) densities in pearl millet grain samples from 11 trials showed significant differences between these two methods for both micronutrients. XRF values were more often higher than the ICP values for both micronutrients, but the differences were significant in only 15–38% genotypes for Fe and in 7–25% genotypes for Zn across the trials. In 82% genotypes the differences between these two methods were ≤6 mg kg−1 for Fe; and in 88% genotypes, the differences were ≤4 mg kg−1for Zn. There were highly significant and high positive correlations between ICP and XRF for both micronutrients. Selection of genotypes above the XRF trial mean for Fe/Zn included at least 30% top-ranking genotypes based on ICP. Therefore, XRF can be used for cost-effective and rapid screening of a large number of grain samples in pearl millet biofortification programs.