Mapping of the leaf rust resistance gene Lr3 on chromosome 6B of Sinvalocho MA wheat

The Lr3 gene for resistance to race 66 of Puccinia recondita present in hexaploid wheat cv. Sinvalocho MA was mapped on chromosome 6B, using intervarietal polymorphic RFLP loci and the Amp-B1 isozyme gene as a centromere marker. The RFLP markers were located mainly in two subregions of chromosome 6BL. Six RFLP loci clustered in the centromeric region and one other, Xmwg798, cosegregated with the Lr3 gene. C-banding analysis of the leaf rust resistant standard 'Sinvalocho MA' line and three naturally occurring susceptible lines of 'Sinvalocho MA' revealed a terminal deletion on 6BL that covered 20% of its length in one susceptible line. Because Xmwg798 was missing in this line, both Xmwg798 and Lr3 were allocated to the deleted segment. Distorted segregations were observed for the proximal markers, suggesting a selection against gametes carrying the centromeric region of 'Sinvalocho MA'.Key words: wheat, RFLP, Lr3 gene, chromosome 6B, C-banding.

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Location of a Triticum speltoides chromosome segment conferring resistance to leaf rust in Triticum aestivum

Genome ◽

10.1139/g90-134 ◽

1990 ◽

Vol 33 (6) ◽

pp. 892-897 ◽

Cited By ~ 30

Author(s):

J. Dvořák ◽

D. R. Knott

Keyword(s):

Triticum Aestivum ◽

Leaf Rust ◽

Wheat Chromosome ◽

Leaf Rust Resistance ◽

Leaf Rust Resistance Gene ◽

Backcross Generation ◽

Transfer Lines ◽

C Banding ◽

Banding Analysis ◽

Speltoides Chromosome

A leaf rust resistant line, 2-9-2, was selected in the fourth backcross generation to Triticum aestivum of an interspecific hybrid, T. aestivum × Triticum speltoides. The resistance segregated independently of T. speltoides leaf rust resistance gene Lr28, previously shown to be incorporated into wheat chromosome 1B in two other transfer lines. Monosomic and telosomic analyses showed that the gene in line 2-9-2, Lr36, was incorporated into the short arm of chromosome 6B. C-banding analysis showed that the homoeologous crossing-over occurred distally to an interstitial C-band in the satellite and linkage analysis showed Lr36 to be tightly linked to the telomeric C-band.Key words: C-banding, physical mapping, linkage, wheat, chromosome 6B, introgression.

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Map-Based Cloning of Leaf Rust Resistance Gene Lr21 From the Large and Polyploid Genome of Bread Wheat

Genetics ◽

10.1093/genetics/164.2.655 ◽

2003 ◽

Vol 164 (2) ◽

pp. 655-664 ◽

Cited By ~ 3

Author(s):

Li Huang ◽

Steven A Brooks ◽

Wanlong Li ◽

John P Fellers ◽

Harold N Trick ◽

...

Keyword(s):

Amino Acid ◽

Leaf Rust ◽

Resistance Gene ◽

Bread Wheat ◽

Rust Resistance ◽

Agronomic Traits ◽

Leaf Rust Resistance ◽

Triticum Aestivum L ◽

Rust Resistance Gene ◽

Leaf Rust Resistance Gene

Abstract We report the map-based cloning of the leaf rust resistance gene Lr21, previously mapped to a generich region at the distal end of chromosome arm 1DS of bread wheat (Triticum aestivum L.). Molecular cloning of Lr21 was facilitated by diploid/polyploid shuttle mapping strategy. Cloning of Lr21 was confirmed by genetic transformation and by a stably inherited resistance phenotype in transgenic plants. Lr21 spans 4318 bp and encodes a 1080-amino-acid protein containing a conserved nucleotide-binding site (NBS) domain, 13 imperfect leucine-rich repeats (LRRs), and a unique 151-amino-acid sequence missing from known NBS-LRR proteins at the N terminus. Fine-structure genetic analysis at the Lr21 locus detected a noncrossover (recombination without exchange of flanking markers) within a 1415-bp region resulting from either a gene conversion tract of at least 191 bp or a double crossover. The successful map-based cloning approach as demonstrated here now opens the door for cloning of many crop-specific agronomic traits located in the gene-rich regions of bread wheat.

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