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United States Department of Agriculture

Agricultural Research Service

Research Project: ALLIUM, CUCUMIS, AND DAUCUS GERMPLASM ENHANCEMENT, GENETICS, AND BIOCHEMISTRY

Location: Vegetable Crops Research Unit

Title: Single nucleotide polymorphisms in linkage disequilibrium with the male-fertility restoration (Ms) locus of onion

Author
item Havey, Michael

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 22, 2013
Publication Date: July 8, 2013
Citation: Havey, M.J. 2013. Single nucleotide polymorphisms in linkage disequilibrium with the male-fertility restoration (Ms) locus of onion. Journal of the American Society for Horticultural Science. 138(4):306-309.

Interpretive Summary: Maintainer lines are used to seed propagate male-sterile lines for the development of hybrid-onion cultivars. The identification of maintainer lines would be more efficient with molecular markers distinguishing genotypes at the nuclear male-fertility restoration (Ms) locus. Ms has been mapped to chromosome 2 of onion, and genetic markers flanking this locus have been identified. However these markers were found to be at or near linkage equilibrium in open-pollinated populations of onion. In this research, near isogenic lines differing for genotypes at Ms were developed and screened for 1,256 single nucleotide polymorphisms (SNPs). Three SNPs were tightly linked on chromosome 2 and remained in linkage disequilibrium with genotypes at Ms among randomly selected plants from three open-pollinated populations of onion. This information will be of use to onion breeders, allowing them to use these SNPs for selection of the recessive ms allele in diverse onion populations, as an aid to development of maintainer lines for hybrid development.

Technical Abstract: Maintainer lines are used to seed propagate male-sterile lines for the development of hybrid-onion cultivars. The identification of maintainer lines would be more efficient with molecular markers distinguishing genotypes at the nuclear male-fertility restoration (Ms) locus. Ms has been mapped to chromosome 2 of onion and linked genetic markers identified. However linkages of markers with Ms were detected using F2 or BC1 families at maximum linkage disequilibrium and, for many markers, their efficacy to predict genotypes at Ms in onion populations at or near linkage equilibrium remains unknown. In this research, near isogenic lines homozygous dominant and recessive at Ms were developed and screened for 932 single nucleotide polymorphisms (SNPs). Three SNPs tightly linked on chromosome 2 remained in linkage disequilibrium with genotypes at Ms among randomly selected plants from three open-pollinated populations of onion, as well as among inbred lines . These SNPs should be useful for selection of the recessive ms allele to aid in the development of maintainer lines for hybrid production.

Last Modified: 9/1/2014
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