Seed parent breeding efficiency of three diverse cytoplasmic-nuclear male-sterility systems in pearl millet

Abstract

Pearl millet (Pennisetum glaucum (L.) R. Br.) hybrids, grown widely in India and to some extent in the US, are all based on an A1 CMS source, leaving the pearl millet hybrids vulnerable to potential disease or insect pest epidemics. A comparison of this CMS system with two additional CMS systems (A4 and A5) in the present study based on isonuclear A-lines (seed parents) and their isonuclear hybrids showed that A-lines with the A4 cytoplasm had much fewer pollen shedders and much reduced selfed seed set in visually assessed non-shedding plants as compared to those with the A1 cytoplasm. A-lines with the A5 cytoplasm had neither any pollen shedders nor did they set any seed when selfed. This showed that the A5 CMS system imparts complete and most stable male sterility, followed by the A4 and A1 CMS systems. The frequency of maintainers, averaged across a diverse range of 26 populations, was highest for the A5 CMS system (98%), followed by the A4 (59%) and the A1 (34%) system indicating the greatest prospects for genetic diversification of A-lines lies with the A5 cytoplasm, and the least with the A1 cytoplasm. Mean grain yield of hybrids with the A1 cytoplasm was 5% more than the A4-system hybrids, while there was no difference between the mean grain yield of hybrids based on A1 and A5 CMS systems. Based on these results, it is suggested that seed parents breeding efficiency will be the greatest with the A5 CMS system, followed by the A4 CMS system, and least with the currently commercial A1 CMS system.