Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: November 1, 1995
Publication Date: N/A
Technical Abstract: The production of hybrid-onion seed is economically feasible through the use of cytoplasmic-genic male-sterility (CMS) systems. Cytoplasmic identifications of a single plant take from four to eight years and are complicated by the segregation of a nuclear gene that restores fertility. Southern analyses of the organellar genomes revealed that many open-pollinated populations possess S-cytoplasm. Amplification by PCR of a fragment carrying an 100-base-pair insertion in the chloroplast DNA of N-cytoplasm is a significantly quicker and cheaper way to determine the cytoplasm of single onion plants. Molecular characterization of N- and S-cytoplasms and frequencies of the nuclear fertility-nonrestoring allele allow breeders to determine the proportion of plants in open-pollinated populations that maintain CMS. Testcrosses demonstrated that this technology significantly reduces the investment required to identify individual maintainer plants. Our efforts to tag the nuclear fertility-restoration locus indicated that more than one locus may condition restoration of male fertility in S-cytoplasmic plants.