Isolation and mapping of microsatellite markers specific for the D genome of bread wheat E. Pestsova, M.W. Ganal, and M.S. Röder Abstract: The potential of Aegilops tauschii, the diploid progenitor of the D genome of wheat, as a source of microsatellite markers for hexaploid bread wheat was investigated. By screening lambda phage and plasmid libraries of Ae. tauschii genomic DNA, dinucleotide microsatellites containing GA and GT motifs were isolated and a total of 65 functional microsatellite markers were developed. All primer pairs that were functional in Ae. tauschii amplified well in hexaploid wheat. Fifty-five loci amplified by 48 primer sets were placed onto a genetic framework map of the refer- ence population of the International Triticeae Mapping Initiative (ITMI) ‘Opata 85’ × ‘W7984’. The majority of microsatellite markers could be assigned to the chromosomes of the D genome of wheat. The distribution of the mark- ers along the chromosomes is random. Chromosomal location of 22 loci nonpolymorphic in the reference population was determined using nullitetrasomic lines of Triticum aestivum ‘Chinese Spring’. The results of this study demonstrate the value of microsatellite markers isolated from Ae. tauschii for the study of bread wheat. The microsatellite markers developed improve the existing wheat microsatellite map and can be used in a wide range of genetic studies and breed- ing programs. Key words: Aegilops tauschii, wheat, molecular markers, genetic map, simple sequence repeats. Résumé : Le potentiel de l’Aegilops tauschii, l’espèce donatrice du génome D du blé, en tant que source de marqueurs microsatellites pour le blé hexaploïde a été étudié. En criblant des banques génomiques (phages lambda et plasmides) de l’Ae. tauschii, des microsatellites dinucléotidiques GA et GT ont été isolés et 65 marqueurs microsatellites fonction- nels ont été développés. Toutes les paires d’amorces qui étaient fonctionnelles chez l’Ae. tauschii ont bien amplifié chez le blé hexaploïde. Cinquante-cinq locus amplifiés à l’aide de 48 paires d’amorces ont été placés sur une carte gé- nétique issue de la population de référence de l’ITMI (« International Triticeae Mapping Initiative »), ‘Opata 85’ × ‘W7984’. La majorité des microsatellites pouvaient être assignés au chromosomes du génome D du blé. La distribution des marqueurs au long des chromosomes était aléatoire. L’emplacement chromosomique des 22 locus monomorphes au sein de la population de référence a été déterminé à l’aide de lignées nulli-tétrasomiques de Triticum aestivum ‘Chinese Spring’. Les résultats de cette étude montrent l’intérêt chez le blé des microsatellites isolés de l’Ae. tauschii. Les mi- crosatellites développés contribuent à améliorer la carte existante du blé et peuvent être employés pour une vaste gamme d’études génétiques et en sélection. Mots clés : Aegilops tauschii, blé, marqueurs moléculaires, carte génétique, répétitions de séquences simples. [Traduit par la Rédaction] Pestsova et al. 697 Introduction Microsatellites or simple sequence repeats (SSR) are tan- dem repeats of 2–4 nucleotides. They are frequent and al- most randomly distributed in most eukaryotic genomes. This makes them desirable markers for genetic mapping. Molecu- lar markers based on microsatellite sequences detect extra high levels of polymorphism and can be easily assayed by PCR (polymerase chain reaction). A highly saturated micro- satellite map published for human consists of about 8000 such markers (Weissenbach 1998). In recent years, microsat- ellite markers were integrated into the existing molecular maps of Arabidopsis (Bell and Ecker 1994), tomato (Areshchenkova and Ganal 1999), rice (Cho et al. 1998), maize (Taramino and Tingey 1996), barley (Liu et al. 1996), wheat (Röder et al. 1998), and other plants. The high-density microsatellite map of bread wheat (Triticum aestivum L. em Thell.) constructed in our labora- tory consists of more than 279 markers (Röder et al. 1998). These microsatellites have been successfully used for the study of genetic diversity (Plaschke et al. 1995; Fahima et al. 1998), testing of authenticity of genetic stocks (Korzun et al. 1997; Peil et al. 1998; Pestsova et al. 2000a), and gene map- ping (Korzun et al. 1998; Peng et al. 1999; Salina et al. 2000). Bread wheat is allohexaploid (2n = 42, AABBDD) and consists of three different genomes A, B, and D. Common wheat is a product of hybridization between the tetraploid wheat T. turgidum L. (2n = 28, AABB) and diploid grass Aegilops tauschii Coss. (2n = 14, DD) (Kihara 1944; Genome 43: 689–697 (2000) © 2000 NRC Canada 689 Corresponding Editor: G.J. Scoles. Received January 4, 2000. Accepted May 23, 2000. Published on the NRC Research Press web site on July 20, 2000. E. Pestsova, 1 M.W. Ganal, and M.S. Röder. Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstraße 3, 06466 Gatersleben, Germany. 1 Author to whom all correspondence should be addressed (e-mail: pestsova@ipk-gatersleben.de).