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GrainGenes Reference Report: GNM-45-737

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Reference	GNM-45-737
Title	Genetic mapping of the Lr20-Pm1 resistance locus reveals suppressed recombination on chromosome arm 7AL in hexaploid wheat
Journal	Genome
Year	2002
Volume	45
Pages	737-744
Author	Neu C Stein N Keller B
Abstract	Summary: The Lr20-Sr15-Pm1 resistance locus in hexaploid wheat confers resistance to three different fungal wheat pathogens (leaf rust, stem rust, and powdery mildew). It was previously localized in the distal region of chromosome arm 7AL. As a first step towards the isolation of this complex locus, we performed molecular mapping of the Lr20 and Pm1 genes in three F2 populations. In two populations, a cluster of 8 and 12 markers, respectively, cosegregated with the resistance genes. In a third population based on a cross between a susceptible lr20 mutant and a resistant cultivar, all clustered markers were monomorphic. However, in this population the recombination frequency proximal to the Lr20 gene was up to 60 times higher, indicating that the complete genetic linkage of the clustered markers is not due to a close physical linkage of the probes but is caused by suppressed recombination. This was supported by the analysis of Triticum monococcum BAC clones where no physical linkage between cosegregating probes was observed. Suppressed recombination at the Lr20-Pm1 locus is likely the result of an alien introgression of chromatin from an unidentified wild relative species or is due to chromosomal rearrangements
External Databases	Pubmed: 12175077
Gene	Pm1 (Triticum) Lr20 (Triticum) Sr15 (Triticum)
Locus	Pm1 Lr20 Sr15
Probe	STS638
Keyword	[ Hide all but 1 of 54 ] alien introgression bac barley canada chromatin chromosomal rearrangements chromosome chromosome arm cluster complexes confers resistance cultivar diploid wheat f-2 population frequencies fungal gene genetic linkage genetic mapping genetic-linkage group-7 chromosomes hexaploid hordeum vulgare introgression isolation leaf rust linkage locus mapping mildew molecular mapping monococcum mutant nematode physical maps pm1 powdery mildew probe probes rearrangements recombination recombination frequency region resistance resistant rust stem stem rust suppressed recombination triticum triticum aestivum triticum monococcum wild wild relative

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