ARS | Publication request: THE EFFICIENCY OF DNA MARKERS TO IDENTIFY CYTOPLASMS AND NUCLEAR GENOTYPES FOR THE DEVELOPMENT OF CMS-MAINTAINER LINES

Submitted to: International Symposium on the Edible Alliaceae
Publication Type: Abstract Only
Publication Acceptance Date: January 30, 2001
Publication Date: N/A

Technical Abstract: The production of hybrid-onion (Allium cepa L.) seed is economically feasible using cytoplasmic-genic male-sterility (CMS) systems. The most widely used source of CMS in onion is conditioned by the interaction of sterile (S) cytoplasm and the homozygous recessive (msms) genotype at a single nuclear male-fertility restoration locus (Ms). Maintainer lines are used to seed propagate male-sterile lines and possess normal (N) male-fertile cytoplasm and the homozygous recessive (msms) genotype at the Ms locus. Conventionally, cytoplasmic determinations of single onion plant can take from 4 to 8 years and are complicated by segregation of the nuclear Ms locus. We previously developed a PCR marker that distinguishes N and S cytoplasms. We now have identified nuclear DNA markers flanking the Ms locus. We determined the genotypes at these flanking molecular markers for commercial inbred families and for S1 families produced by self-pollinating randomly selected bulbs from three open-pollinated (OP) populations. The S0 bulbs used to generate the S1 families were testcrossed to male-sterile plants to score genotypes at the Ms locus. We are working to convert molecular markers flanking the Ms locus to nonradioactive PCR-based detection systems.