Mining genetic diversity in wild barley for disease resistance

Russell, James Michael (2024) Mining genetic diversity in wild barley for disease resistance. Doctoral thesis, University of East Anglia.

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Abstract

The discovery and characterisation of disease resistance (R) genes is essential to protect crop yields against the endemic threat of pathogens. Wild relatives encompass diverse germplasm and are therefore rich targets for R gene mining. The wild barley diversity collection (WBDC), containing 318 Hordeum vulgare subsp. spontaneum accessions, was screened for resistance to five North American physiological races of the barley stripe rust fungus, Puccinia striiformis f. sp. hordei, (Psh). Approximately half (162 accessions) resisted at least one race, including 12 accessions resistant to all tested isolates. Subsequent screening with the UK Psh isolate B01/2 found it to be avirulent against the 12 accessions resistant in all previous tests. Genetic mapping of Psh B01/2 resistance in F2 populations derived from nine WBDC accessions found eight (WBDC008, WBDC068, WBDC085, WBDC109, WBDC110, WBDC241, WBDC247 and WBDC343) to carry a single dominant or semi-dominant resistance locus on the long arm of chromosome 7H (Rps12) and one (WBDC350) to carry a dominant resistance locus on the short arm of chromosome 2H (Rps14). The proximity of Rps12 to the previously reported major effect Psh resistance gene in the accession BISON7H prompted mapping of this locus, refining it to a region proximal to Rps12 and showing its recessive inheritance in an F2 population (rps13). Following F2:3 population based fine mapping of the two WBDC-derived genes, candidates were identified in the reference genome and evaluated based on RNA-seq data. Of eleven predicted genes in the 234 kb Rps12 region, a single NLR was identified as the strongest candidate. The 1.7 Mb rps13 region contains 91 predicted genes, including a cluster of NLRs and the homologue to Rph3. All three predicted genes in the 22.5 kb Rps14 region are of categories not previously associated with fungal pathogen resistance. Cloning and validation was initiated for a single candidate at each locus.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > The Sainsbury Laboratory
Depositing User:	James Tweddle
Date Deposited:	20 Feb 2025 10:13
Last Modified:	20 Feb 2025 10:13
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98543
DOI:

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