Application of BARE -1 retrotransposon markers to the mapping of a major resistance gene for net blotch in barley
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ORIGINAL PAPER
O. Manninen á R. Kalendar J. Robinson á A. H. Schulman
Application of BARE-1 retrotransposon markers to the mapping of a major resistance gene for net blotch in barley Received: 23 December 1999 / Accepted: 28 June 2000 / Published online: 19 August 2000 Ó Springer-Verlag 2000
Abstract Net blotch, which is caused by the fungus Pyrenophora teres Drechs. f. teres Smedeg., presents a serious problem for barley production worldwide, and the identi®cation and deployment of sources of resistance to it are key objectives for many breeders. Here, we report the identi®cation of a major resistance gene, accounting for 65% of the response variation, in a cross between the resistant line CI9819 and the susceptible cv. Rol®. The resistance gene was mapped to chromosome 6H with the aid of two recently developed systems of retrotransposon-based molecular markers, REMAP and IRAP. A total of 239 BARE-1 and Sukkula retrotransposon markers were mapped in the cross, and the 30-cM segment containing the locus with signi®cant resistance eect contained 26 of the markers. The type and local density of the markers should facilitate future map-based cloning of the resistance gene as well as manipulation of the resistance through backcross breeding. Key words BARE-1 retrotransposon á Barley á Net blotch resistance á Linkage mapping á Quantitative trait locus (QTL)
Communicated by R. Hagemann R. Kalendar á A. H. Schulman (&) Institute of Biotechnology, University of Helsinki, Plant Genomics Laboratory, Viikki Biocenter, P.O. Box 56, Viikinkaari 6, FIN-00014 Helsinki, Finland E-mail: alan.schulman@helsinki.® Fax: +358-9-19158952 O. Manninen á J. Robinson Agricultural Research Centre of Finland, Plant Production Research, Crops and Soil, FIN-31600 Jokioinen, Finland The ®rst two authors contributed equally to this work
Introduction Net blotch of barley (Hordeum vulgare L.), which is caused by the fungal phytopathogen Pyrenophora teres Drechs. f. teres Smedeg., constitutes one of the most serious constraints on barley production world-wide (Shipton et al. 1973), reaching as far north as the Arctic Circle in Finland (MaÈkelaÈ 1975). It may lead to grain yield losses of up to 40% in severe infections (Steenson 1997). Deployment of improved host-plant resistance is a principal goal of breeders in many countries (Robinson and Jalli 1996, 1997; Jalli and Robinson 2000). Several barley lines with major-gene resistance to net blotch have been identi®ed. The results of classical genetic analyses indicate that resistance is controlled by 1±3 loci, depending on the barley accession and the net blotch isolate used for testing (Mode and Schaller 1958; Wilcoxson et al. 1992; Douiyssi et al. 1996; Ho et al. 1996). The genetic background of the susceptible parent used in crosses and the infection environment both in¯uence the host resistance reaction (Khan 1969). At least three independently segregating resistance genes, Rpt1, Rpt2 and Rpt3, have been localized by trisomic analysis on chromosomes 3H, 1H, and 2H, respectively (Bockelman et a
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