Efficacy of Molecular Markers Jnurf13 and AcPms1 for Prediction of Genotypes at the Nuclear Ms Locus in Three Open-pollinated Populations of Onion from North America

Abstract

Seed of hybrid onion (Allium cepa L.) is produced using cytoplasmic male sterility (CMS). For the most widely used source of onion CMS, male sterility is conditioned by the interaction of male sterile (S) cytoplasm and the homozygous recessive genotype at the nuclear male fertility locus Ms. Because of the biennial generation time of onion, classical crossing and segregation analyses take years to establish cytoplasms and genotypes at Ms. Numerous molecular markers have been developed to distinguish onion cytoplasms and estimate genotypes at Ms. Two nuclear markers (jnurf13 and AcPms1) have been reported to cosegregate with Ms and correctly predict genotypes in commercial breeding lines and diverse onion germplasm; however, these markers were less predictive for open-pollinated (OP) populations from India. We evaluated the efficacy of jnurf13 and AcPms1 to correctly classify genotypes at Ms using 144 random plants from three OP populations of long-day onion from North America. No recombination events were detected between AcPms1 and the Ms locus and three events occurred between jnurf13 and Ms. Our results support either marker as a useful tool to predict genotypes at Ms in North American populations of onion, with AcPms1 being the better of the two.