Two haplotypes of resistance gene analogs have been conserved during evolution at the leaf rust resistance locus Lr10 in wild and cultivated wheat

Scherrer, Beatrice; Keller, Beat; Feuillet, Catherine

doi:10.1007/s10142-002-0051-9

Cited by 18 publications

(26 citation statements)

References 22 publications

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“…Haplotype H1 is defined by the presence of the two full-length rga1 and rga2 genes, whereas in haplotype H2, rga1 is absent and only a truncated LRR domain of rga2 can be detected (ref. 25 and Fig. 1A).…”

Section: Isolation Of Two Candidate Genes For Lr10 In Hexaploidmentioning

confidence: 79%

“…Two RGAs, named rga1 and rga2, have been previously identified in a genomic region of T. monococcum DV92 spanning the Lr10 resistance locus in T. aestivum, ThatcherLr10 (14,15). To test whether these genes are the best candidate genes for Lr10, we have analyzed the Lr10 locus at the molecular level in the wheat gene pool (25). Southern analysis of 113 wild and cultivated diploid and polyploid wheat lines has revealed the presence of two characteristic haplotypes on chromosome 1AS.…”

Section: Isolation Of Two Candidate Genes For Lr10 In Hexaploidmentioning

confidence: 99%

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Map-based isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat ( Triticum aestivum L.) genome

Feuillet

Travella

Stein

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

461

300

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More than 50 leaf rust resistance (Lr) genes against the fungal pathogen Puccinia triticina have been identified in the wheat gene pool, and a large number of them have been extensively used in breeding. Of the 50 Lr genes, all are known only from their phenotype and͞or map position except for Lr21, which was cloned recently. For many years, the problems of molecular work in the large (1.6 ؋ 10 10 bp), highly repetitive (80%), and hexaploid bread wheat (Triticum aestivum L.) genome have hampered map-based cloning. Here, we report the isolation of the Lr gene Lr10 from hexaploid wheat by using a combination of subgenome map-based cloning and haplotype studies in the genus Triticum. Lr10 is a single-copy gene on chromosome 1AS. It encodes a CC-NBS-LRR type of protein with an N-terminal domain, which is under diversifying selection. When overexpressed in transgenic wheat plants, Lr10 confers enhanced resistance to leaf rust. Lr10 has similarities to RPM1 in Arabidopsis thaliana and to resistance gene analogs in rice and barley, but is not closely related to other wheat Lr genes based on Southern analysis. We conclude that map-based cloning of genes of agronomic importance in hexaploid wheat is now feasible, opening perspectives for molecular bread wheat improvement trough transgenic strategies and diagnostic allele detection.

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Section: Isolation Of Two Candidate Genes For Lr10 In Hexaploidmentioning

confidence: 79%

Section: Isolation Of Two Candidate Genes For Lr10 In Hexaploidmentioning

confidence: 99%

Map-based isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat ( Triticum aestivum L.) genome

Feuillet

Travella

Stein

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

461

300

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“…Analysis of orthologous regions in different species usually relies on the assumption that the genotypes chosen for the analysis represent the entire species. However, exceptional haplotype variation was reported recently at orthologous bz loci in maize (Fu and Dooner, 2002), and in wheat, RFLP studies have detected the existence of different haplotypes in diploid wild wheat species that were transmitted to different genotypes of hexaploid wheat (Scherrer et al, 2002). We have found similar evidence for polymorphic haplotypes at the SFR159 loci in different T. monococcum, T. urartu, and T. dicoccoides accessions (our unpublished results), and we are currently investigating the presence of these haplotypes in hexaploid wheat.…”

Section: The Intergenic Regions Of the Wheat Genome Evolve Very Rapidlymentioning

confidence: 99%

Rapid Genome Divergence at Orthologous Low Molecular Weight Glutenin Loci of the A and Am Genomes of Wheat[W]

et al. 2003

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To study genome evolution in wheat, we have sequenced and compared two large physical contigs of 285 and 142 kb covering orthologous low molecular weight (LMW) glutenin loci on chromosome 1AS of a diploid wheat species ( Triticum monococcum subsp monococcum ) and a tetraploid wheat species ( Triticum turgidum subsp durum ). Sequence conservation between the two species was restricted to small regions containing the orthologous LMW glutenin genes, whereas Ͼ 90% of the compared sequences were not conserved. Dramatic sequence rearrangements occurred in the regions rich in repetitive elements. Dating of long terminal repeat retrotransposon insertions revealed different insertion events occurring during the last 5.5 million years in both species. These insertions are partially responsible for the lack of homology between the intergenic regions. In addition, the gene space was conserved only partially, because different predicted genes were identified on both contigs. Duplications and deletions of large fragments that might be attributable to illegitimate recombination also have contributed to the differentiation of this region in both species. The striking differences in the intergenic landscape between the A and A m genomes that diverged 1 to 3 million years ago provide evidence for a dynamic and rapid genome evolution in wheat species.

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“…The leaf rust resistance gene Lr10 was recently isolated ) using a combination of subgenome mapbased cloning (Stein et al 2000;Wicker et al 2001) and haplotype studies (Scherrer et al 2002). Lr10 is closely associated with a second resistance gene analog (RGA2), but the two genes are very different from each other at the molecular level .…”

mentioning

confidence: 99%

“…Lr10 is closely associated with a second resistance gene analog (RGA2), but the two genes are very different from each other at the molecular level . Analysis of the wheat gene pool by Southern hybridization revealed the presence of two groups of lines with distinct haplotypes (H1 and H2) at the Lr10 locus, defined by the presence (H1) or absence (H2) of the two full-length Lr10 and RGA2 genes on chromosome 1A (Scherrer et al 2002). Thus, the Lr10 resistance locus differs from most resistance loci in plants, where clusters of closely related genes are present, but is similar to the Arabidopsis RPM1 locus (Grant et al 1995).…”

mentioning

confidence: 99%

Ancient haplotypes resulting from extensive molecular rearrangements in the wheat A genome have been maintained in species of three different ploidy levels

Isidore¹,

Scherrer²,

Chalhoub³

et al. 2005

Genome Res.

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Plant genomes, in particular grass genomes, evolve very rapidly. The closely related A genomes of diploid, tetraploid, and hexaploid wheat are derived from a common ancestor that lived <3 million years ago and represent a good model to study molecular mechanisms involved in such rapid evolution. We have sequenced and compared physical contigs at the Lr10 locus on chromosome 1AS from diploid (211 kb), tetraploid (187 kb), and hexaploid wheat (154 kb). A maximum of 33% of the sequences were conserved between two species. The sequences from diploid and tetraploid wheat shared all of the genes, including Lr10 and RGA2 and define a first haplotype (H1). The 130-kb intergenic region between Lr10 and RGA2 was conserved in size despite its activity as a hot spot for transposon insertion, which resulted in >70% of sequence divergence. The hexaploid wheat sequence lacks both Lr10 and RGA2 genes and defines a second haplotype, H2, which originated from ancient and extensive rearrangements. These rearrangements included insertions of retroelements and transposons deletions, as well as unequal recombination within elements. Gene disruption in haplotype H2 was caused by a deletion and subsequent large inversion. Gene conservation between H1 haplotypes, as well as conservation of rearrangements at the origin of the H2 haplotype at three different ploidy levels indicate that the two haplotypes are ancient and had a stable gene content during evolution, whereas the intergenic regions evolved rapidly. Polyploidization during wheat evolution had no detectable consequences on the structure and evolution of the two haplotypes.

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Two haplotypes of resistance gene analogs have been conserved during evolution at the leaf rust resistance locus Lr10 in wild and cultivated wheat

Cited by 18 publications

References 22 publications

Map-based isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat ( Triticum aestivum L.) genome

Map-based isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat ( Triticum aestivum L.) genome

Rapid Genome Divergence at Orthologous Low Molecular Weight Glutenin Loci of the A and Am Genomes of Wheat[W]

Ancient haplotypes resulting from extensive molecular rearrangements in the wheat A genome have been maintained in species of three different ploidy levels

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