Inbreeding Effects on Grain Iron and Zinc Concentrations in Pearl Millet

Abstract

The magnitude, direction, and pattern of inbreeding effects on trait expression in selfing generations have a direct bearing on single‐plant and progeny‐based selection efficiency. In the present study on a pearl millet [Pennisetum glaucum (L.) R. Br.] biofortification initiative, initial random mated S0 bulks of three diverse composites and their S1 to S4 population bulks derived from four generations of selfing were evaluated for 2 yr under irrigated and terminal drought stress for iron (Fe) and zinc (Zn) concentrations. Both Fe and Zn concentrations were higher under terminal drought than under irrigated condition. Inbreeding had no significant effect on Fe and Zn concentrations in one composite and showed significant though marginal increase of both micronutrients in two composites. This finding, not unexpected, was in conformity with the earlier reports of predominantly additive gene effects and marginal partial dominance of genes determining low concentrations of these micronutrients observed in a low frequency of hybrids. The patterns of genetic changes in Fe concentration due to inbreeding were highly significantly and positively correlated with those in Zn concentration in all three composites. These results indicate that simultaneous single‐plant and progeny‐based early generation selection for Fe and Zn concentrations is likely to be effective to enhance the breeding efficiency for these micronutrients in pearl millet.

Generation Mean Analysis Reveals the Predominant Gene Effects for Grain Iron and Zinc Contents in Pearl Millet

“…In addition, the absence of BPH, along with non-significant ID, for all the four crosses tends to be compatible with the additive genetic effect for grain Fe and Zn contents. Notably, the non-significant ID detected for Fe and Zn contents in grains in the present study is consistent with the findings of a previous study on pearl millet (Rai et al, 2017). The degree of dominance for the grain Fe content was negligible, whereas that for the grain Zn content was either close to or higher than one during E 1 and E 2 , indicating the some role of partial dominance as non-additive genetic effects.…”

Conventional and Molecular Breeding Approaches for Biofortification of Pearl Millet

“…This pattern of genetic control suggested that the selection for higher grain micronutrients should be commenced in earlier generation while agronomic superiority can be selected in later generations. Interestingly, unlike yield traits, inbreeding has no adverse effect on micronutrient content in pearl millet (Rai et al 2017).…”

“…Development of inbred lines with high Fe and Zn depends on the level of and variability for these micronutrients in the base population (whether F 2 s or OPVs or composites), and on the magnitude, direction, and pattern of inbreeding effects. It has been observed that inbreeding had either no significant effect or had marginally increased both micronutrients (Rai et al 2017). In contrast to the low heritability and inbreeding depression of grain yield, micronutrient contents are highly heritable and hybrids can be readily improved through hybrid parents breeding.…”