Abstract
Forty-five African or Asian origin pearl millet populations bred either in Africa or Asia were investigated to generate information on heterotic pools. They were clustered into seven groups (G1 to G7) when genotyped, using 29 highly polymorphic SSRs. Fourteen parental populations representing these seven marker-based groups were crossed in diallel mating design to generate 91 population hybrids. The hybrids evaluated at three locations in India showed mean panmictic mid-parent heterosis (PMPH) and better-parent heterosis (PBPH) for grain yield ranging from − 21.7 to 62.08% and − 32.51 to 42.99%, respectively. Higher grain yield and heterosis were observed in G2 × G6 (2462 kg ha−1, 43.2%) and G2 × G5 (2455 kg ha−1, 42.8%) marker group crosses compared to the most popular Indian open-pollinated variety (OPV) ICTP 8203. Two heterotic groups, Pearl millet Population Heterotic Pool-1 (PMPHP-1) comprising G2 populations and Pearl millet Population Heterotic Pool-2 (PMPHP-2) comprising G5 and G6 populations, were identified based on hybrid performance, heterosis and combining ability among marker group crosses. Population hybrids from two heterotic groups, PMPHP-1 × PMPHP-2 demonstrated PMPH of 14.75% and PBPH of 6.8%. Populations of PMPHP-1 had linkages with either African or Asian origin populations, whereas PMPHP-2 composed of populations originating in Africa and later bred for Asian environments. Results indicated that parental populations from the two opposite heterotic groups can be used as base populations to derive superior inbred lines to develop high yielding hybrids/cultivars.
Highlights
IntroductionOver the past 45 years, breeders at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) have developed a diverse range of gene pools, populations, trait-based composites and open-pollinated variety (OPV) using germplasm originating in Africa and/or A sia[4,26]
Marker groups G4, G5, G6 and G7 were dominated by a majority of Af-As (African origin-Asian bred) populations, while Af-Af (African origin-African bred) and As-As (Asian origin-Asian bred) populations were distributed across all the seven groups (Fig. 1)
Population differentiation (Fst) values in the Analysis of molecular variance (AMOVA) were found significant between seven marker groups, indicating they are significantly different from each other (Table 3)
Summary
Over the past 45 years, breeders at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) have developed a diverse range of gene pools, populations, trait-based composites and OPVs using germplasm originating in Africa and/or A sia[4,26] These ICRISAT-developed populations have shown significant heterosis for grain yield and linked traits[27,28,29]. This evidence of higher heterosis using diverse pearl millet germplasms suggested the identification of heterotic groups to enhance current levels of genetic gain. A recent study on West African pearl millet populations failed to identify heterotic groups and found high levels of genetic admixture in the germplasm that could be the reason[24]. The same set of African and Asian origin/bred pearl millet populations were further investigated to generate information on patterns of heterotic pools, whose results are being reported here
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