Dissection of the Barley 2L1.0 Region Carrying the ‘Laevigatum’ Quantitative Resistance Gene to Leaf Rust Using Near-Isogenic Lines (NIL) and subNIL

Marcel, T C and Aghnoum, R and Durand, J and Varshney, R K and Niks, R E (2007) Dissection of the Barley 2L1.0 Region Carrying the ‘Laevigatum’ Quantitative Resistance Gene to Leaf Rust Using Near-Isogenic Lines (NIL) and subNIL. Molecular Plant-Microbe Interactions, 20 (12). pp. 1604-1615. ISSN 0894-0282

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Partial resistance to leaf rust (Puccinia hordei G. H. Otth) in barley is a quantitative resistance that is not based on hypersensitivity. This resistance hampers haustorium formation, resulting in a long latency period in greenhouse tests. The three most consistent quantitative trait loci (QTL) uncovered in the L94 × ‘Vada’ mapping population were introgressed by marker-assisted backcrossing into the susceptible L94 background to obtain near-isogenic lines (NIL). We also developed the reciprocal Vada- NIL for the susceptibility alleles of those QTL. The QTL Rphq2 affected latency period of P. hordei more than the QTL Rphq3 and Rphq4. The NIL confirmed the contribution of Rphq2 to partial resistance by prolonging the latency period by 28 h on L94-Rphq2 and shortening the latency period by 23 h on Vada-rphq2. On the basis of flanking restriction fragment length polymorphism-based markers, Rphq2 appeared to be located near the telomeric end of the long arm of chromosome 2H, in a physical region of high recombination, making it the target QTL for map-based cloning. Microscopic observations on the NIL confirmed the nonhypersensitive nature of the resistance conferred by Rphq2. A high-resolution genetic map of the Rphq2 region was constructed using a population of 38 subNIL with overlapping L94 introgressions in Vada background across the region. Rphq2 mapped approximately 2 centimorgans (cM) proximal from the MlLa locus. By bulked segregant analysis and use of synteny with rice, we developed additional markers and fine-mapped Rphq2 to a genetic interval of 0.11 cM that corresponds to a stretch of sequence of, at most, 70 kb in rice. Analysis of this rice sequence revealed predicted genes encoding two proteins with unknown function, retrotransposon proteins, peroxidase proteins, and a protein similar to a mitogen-activated protein kinase kinase kinase (MAP3K). Possible homologs of those peroxidases and MAP3K in barley are candidates for the gene that contributes to partial resistance to P. hordei.

Item Type: Article
Uncontrolled Keywords: Additional keywords: Blumeria graminis f. sp. hordei, comparative mapping, Hordeum vulgare L., substitution mapping.
Subjects: Others > Plant Pathology
Others > Agriculture-Farming, Production, Technology, Economics
Depositing User: Library ICRISAT
Date Deposited: 25 Oct 2011 13:30
Last Modified: 02 Jan 2012 07:41
URI: http://oar.icrisat.org/id/eprint/3006
Official URL: http://dx.doi.org/10.1094/MPMI-20-12-1604
Funders: Dutch Organization for Scientific Research, European Commission
Acknowledgement: This project was sponsored by the Dutch Organization for Scientific Research (NWO, project number 809.36.001) and is being supported by the European Commission through the sixth framework program’s integrated project, BIOEXPLOIT (contract number FOOD-CT-2005-513959). We thank M. S. Hovmøller of the Danish Institute of Agricultural Sciences for providing the powdery mildew isolate C15 carrying avirulence to MlLa; N. Stein and M. Röder of the Institute of Plant Genetics and Crop Plant Research (IPK) for providing primer sequences of GBM- and GBMS-microsatellite markers; B. Gorguet, M. T. Ta, and G. R. Rodenas for assistance in developing the near-isogenic lines; and A. Vels for technical assistance in the greenhouse activities
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