Development and validation of molecular markers linked to an Aegilops umbellulata–derived leaf-rust-resistance gene, Lr9, for marker-assisted selection in bread wheat

An Aegilops umbellulata–derived leaf-rust-resistance gene, Lr9, was tagged with 3 random amplified polymorphic DNA (RAPD) markers, which mapped within 1.8 cM of gene Lr9 located on chromosome 6BL of wheat. The markers were identified in an F2 population segregating for leaf-rust resistance, which was generated from a cross between 2 near-isogenic lines that differed in the alien gene Lr9 in a widely adopted agronomic background of cultivar 'HD 2329'. Disease phenotyping was done in controlled environmental conditions by inoculating the population with the most virulent pathotype, 121 R63-1 of Puccinia triticina. One RAPD marker, S5550, located at a distance of 0.8 ± 0.008 cM from the Lr9 locus, was converted to sequence-characterized amplified region (SCAR) marker SCS5550. The SCAR marker was validated for its specificity to gene Lr9 against 44 of the 50 known Lr genes and 10 wheat cultivars possessing the gene Lr9. Marker SCS5550 was used with another SCAR marker, SCS73719, previously identified as being linked to gene Lr24 on a segregating F2 population to select for genes Lr9 and Lr24, respectively, demonstrating the utility of the 2 markers in marker-assisted gene pyramiding for leaf-rust resistance in wheat.Key words: wheat, leaf rust resistance, Lr9, Lr24, RAPD, SCAR.

Download Full-text

SCAR marker tagged to the alien leaf rust resistance gene Lr19 uniquely marking the Agropyron elongatum-derived gene Lr24 in wheat: a revision

Plant Breeding ◽

10.1111/j.1439-0523.2004.00971.x ◽

2004 ◽

Vol 123 (5) ◽

pp. 417-420 ◽

Cited By ~ 24

Author(s):

K. V. Prabhu ◽

S. K. Gupta ◽

A. Charpe ◽

S. Koul

Keyword(s):

Leaf Rust ◽

Resistance Gene ◽

Rust Resistance ◽

Scar Marker ◽

Leaf Rust Resistance ◽

Rust Resistance Gene ◽

Leaf Rust Resistance Gene ◽

Agropyron Elongatum

Download Full-text

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.

Download Full-text