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United States Department of Agriculture

Agricultural Research Service

Title: Selection Favors the Dominant Ms Allele in Open Pollinated Onion Populations Possessing S-Cytoplasm

Authors
item Gokce, Ali Fuat - ULUDAG UNIV GORUKLE BURSA
item Havey, Michael

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 13, 2005
Publication Date: September 26, 2005
Citation: Gokce, A., Havey, M.J. 2005. Selection favors the dominant MS allele in open pollinated onion populations possessing S-Cytoplasm. Genetic Resources and Crop Evolution. 53:1495-1499. Available: http://www.springerlink.com/(hb4hbqzcpsbiyi45hb1lw145)/app/home/contribution.asp?referrer=parent&backto=issue,81,87;searcharticlesresults,2,2;

Interpretive Summary: Onion was historically seed propagated by open pollination (OP). Cytoplasmic-genic male sterility (CMS) encourages outcrossing among individual onion plants. The most common source of CMS in onion is conditioned by the interaction of sterile (S) cytoplasm with a single nuclear male-fertility restoration (Ms) locus. We previously reported that the majority of OP onion populations possess normal (N) male-fertile cytoplasm and varying frequencies of the dominant Ms allele. It was unclear why N-cytoplasmic onion populations possess relatively high frequencies of the Ms allele, which has no obvious function. We used computer simulations to estimate changes in allelic frequencies at Ms for onion populations. The models revealed selection against the recessive ms allele over generations in onion populations. These results are consistent with field and molecular analyses and are of theoretical interest to plant breeders.

Technical Abstract: Onion was historically seed propagated by open pollination (OP) with cytoplasmic-genic male sterility (CMS) and protandry encouraging outcrossing among individual onion plants. The most common source of CMS in onion is conditioned by the interaction of sterile (S) cytoplasm with a single nuclear male-fertility restoration (Ms) locus. We previously reported that the majority of OP onion populations possess normal (N) male-fertile cytoplasm and varying frequencies of the dominant Ms allele. It was unclear why N-cytoplasmic onion populations possess relatively high frequencies of the Ms allele, which has no obvious function. We used computer simulations to estimate changes in allelic frequencies at Ms for onion populations possessing S cytoplasm or a mixture of N and S cytoplasms, and to determine if frequencies of the Ms allele stay constant or change. The models revealed selection against the recessive ms allele over generations in onion populations possessing S-cytoplasm and varying amounts of self pollination and inbreeding depression. These models were consistent with field and molecular analyses documenting that N cytoplasm and the dominant Ms allele predominate in OP onion populations.

Last Modified: 9/2/2014
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