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Short allele dominance as a source of heterozygote deficiency at microsatellite loci: experimental evidence at the dinucleotide locus Gv1CT in Gracilaria gracilis (Rhodophyta)

Authors

  • R. WATTIER,

    1. Laboratoire de Génétique et Evolution des Populations Végétales, URA-CNRS 1185, GDR-CNRS-IFREMER 1002, Université de Lille I, Bât. SN2, F-59655 Villeneuve d’Ascq Cedex, France
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  • C. R. ENGEL,

    1. Laboratoire de Génétique et Evolution des Populations Végétales, URA-CNRS 1185, GDR-CNRS-IFREMER 1002, Université de Lille I, Bât. SN2, F-59655 Villeneuve d’Ascq Cedex, France
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  • P. SAUMITOU-LAPRADE,

    1. Laboratoire de Génétique et Evolution des Populations Végétales, URA-CNRS 1185, GDR-CNRS-IFREMER 1002, Université de Lille I, Bât. SN2, F-59655 Villeneuve d’Ascq Cedex, France
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  • M. VALERO

    1. Laboratoire de Génétique et Evolution des Populations Végétales, URA-CNRS 1185, GDR-CNRS-IFREMER 1002, Université de Lille I, Bât. SN2, F-59655 Villeneuve d’Ascq Cedex, France
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M. Valero Fax: +33-03-20-43-69-79; E-mail: Valero@univ-lille1.fr

Abstract

In this study, we compared the genotypes obtained at a microsatellite locus using two methods of amplification and detection of variation in a set of individuals belonging to the red alga haplo-diploid species, Gracilaria gracilis. The methods varied in their capacity to detect longer alleles in heterozygotes, resulting in an apparent heterozygote deficiency. We attributed this bias in favour of short alleles to competition leading to the preferential amplification of shorter alleles (short allele dominance). To test this hypothesis, we created artificial heterozygotes (mixtures of two haploid DNA samples) and showed that long alleles already less intense than short alleles, ‘suffer’ more from being in association.

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