Short Communication Identification of microsatellite markers for a leaf rust resistance gene introgressed into common wheat from Triticum timopheevii I. Leonova 1 , A. Bo ¨rner 2,4 , E. Budashkina 1 , N. Kalinina 1 , O. Unger 3 , M. Ro ¨der 2 and E. Salina 1 1 InstituteofCytologyandGenetics,RussianAcademyofSciences,Lavrentievaave.10,Novosibirsk,630090,Russia; 2 Institut fu¨r Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstr. 3, D-06466 Gatersleben; 3 NORDSAAT Saatzuchtge- sellschaftmbH,Hauptstrasse1,D-38895Bo¨hnshausen,Germany; 4 Correspondingauthor,E-mail:boerner@ipk-gatersleben.de With 1 figure Received March 17, 2003/Accepted May 27, 2003 Communicated by P. Wehling Abstract Thetetraploidwheat Triticum timopheevii Zhuk(A t A t GG)isknownas a source of genes determining resistance to many diseases. An introgressive line 842, with durable resistance to leaf rust was established by crossing T. aestivum cv. ÔSaratovskaya29Õ with T. tim- opheevii ssp. viticulosum and used for mapping leaf rust resistance genes. Molecular analysis of the line 842 with polymorphic microsat- ellite markers detected introgressions of T. timopheevii into the homoeologous group 2 chromosomes of common wheat. Transloca- tion breakpoints of introgressed fragments were localized between the markers Xgwm95 and Xgwm817 on chromosome 2A, as well as Xgwm1128 and Xgwm1067 on chromosome 2B. Linkage analysis demonstratedtheassociationofdiseaseresistanceattheseedlingstage with chromosome 2A. The gene was found to be linked with marker Xgwm817 atageneticdistanceof1.5cM.Thealienleafrustresistance gene was temporarily designated as lrTt1. Key words: Triticum timopheevii — Puccinia recondita — chromosomelocalization—diseaseresistance—introgressive lines — microsatellite markers Leaf rust caused by Puccinia recondita Rob. Ex Desm. f. ssp. tritici Eriks is one of the most important wheat diseases throughout the world. The development of commercial vari- eties resistant to leaf rust has been proven to be an efficient method for controlling this disease. Nowadays, about 50 leaf rust resistance (Lr) genes have been reported for hexaploid wheat(McIntoshetal.1998),butmostofthemarenolonger effective and, therefore, of limited utility for wheat breeding. Many wild relatives and related species can be successfully usedassourcesofpathogenresistancegenes.Sofar,morethan 20 Lr genes have been introduced from Aegilops, Agropyron, Secale and various Triticum species into common wheat (Schachermayr et al. 1995, Friebe et al. 1996, Cenci et al. 1999, Xie et al. 2003). Among the relatives of bread wheat, there is a unique endemic species, Triticum timopheevii (A t A t GG), occurring in thesouthregionoftheCaucasus(Georgia).Itischaracterized by a complex resistance to many diseases. The T. timopheevii wheats have already been used as a source of resistance genes forcommonwheatandgenesforresistancetostemrust(Sr36), powdery mildew (Pm2, Pm6, Pm27)andleafrust(Lr18)have been exploited (Jørgensen and Jensen 1973, Yamamori 1994, Ja¨rve et al. 2000). Alien introgressions can easily be identified by the use of molecular marker techniques. Among various molecular markers, simple sequence repeat or microsatellite markers havebeenshowntobeefficienttoolsfortheanalysisofhybrid genomes because of a high level of polymorphism and chromosome specificity (Ro¨der et al. 1995, 1998). The aim of thepresentstudywasthemappingofleafrustresistancegenes, derived from T. timopheevii, by using microsatellite markers. Plant materials: The leaf rust resistant introgression line 842 was obtainedfromthecrossbetween T. aestivum cv. ÔSaratovskaya29Õ and T. timopheevii ssp. viticulosum, followed by a single backcross of the F 1 progeny to ÔSaratovskaya 29Õ and sampling cytologically stable resistantplantsintheBC 1 F 4 –BC 1 F 7 .Thelinehasnowbeenadvanced byselfpollinationtoBC 1 F 15 .Theline842ischaracterizedbydurable resistance to a population of leaf rust pathogen races, and it was crossed with the susceptible cv. ÔSkalaÕ to provide an F 2 population consistingof359individualstobeusedformolecularmarkeranalysis. The test for pathogen resistance at seedling stage was performed by scoring the average infestation of the F 3 progeny. Resistance tests: Twenty seedlings per F 3 family were grown in a greenhouse and inoculated with two leaf rust races containing all the virulences present in Europe (1, 2a, 2b, 2c, 3bg, 3ka, 10, 11, 13, 14a, 14b,15,16,17,18,20,21,23,26,28,30,32,33,37,38).Theseedling reaction was scored on a scale from 1 ¼ completely resistant to 9 ¼ highlysusceptible.Forlinkageanalysisscores1to4wereregarded as resistant and scores 5 to 9 as susceptible. Microsatellite analysis: DNA extraction was performed on individual F 2 plants according to Plaschke et al. (1995). Procedures for micro- satellite analysis, the characteristics and chromosome localization of microsatelliteprimers,andtheprotocolforpolymerasechainreaction (PCR) are described by Ro¨der et al. (1998). Before analysing the F 2 population,theparentalgenotypes(line842, ÔSkalaÕ and ÔSaratovskaya 29Õ) were tested for polymorphism. Linkage analysis: Linkage between the microsatellite markers and the resistancetoleafrustwasanalysedby MAPMAKER version 2.0 (Lander et al. 1987). Apreviousmolecularanalysisof24hybridlines(T. aestivum · T. timopheevii) using microsatellite markers allowed the chromosomal localization of T. timopheevii alien fragments Plant Breeding 123, 93—95 (2004) Ó 2004 Blackwell Verlag, Berlin ISSN 0179-9541 U. S. Copyright Clearance Center Code Statement: 0179–9541/2004/2301–0093 $ 15.00/0 www.blackwell-synergy.com