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Research Project: Genetic Improvement of Small Grains for Biotic and Abiotic Stress Tolerance and Characterization of Pathogen Populations

Location: Plant Science Research

Title: Fine mapping of barley locus Rps6 conferring resistance to wheat stripe rust

Author
item LI, KUN - Shandong Agricultural University
item HEGARTY, JOSHUA - University Of California
item ZHANG, CHAOZHONG - Shandong Agricultural University
item WAN, ANMIN - Washington State University
item WU, JIAJIE - University Of California
item Brown-Guedira, Gina
item Chen, Xianming
item MUNOZ-AMATRIAIN, MARIA - University Of California
item FU, DAOLIN - Shandong Agricultural University
item DUBCOVSKY, JORGE - Howard Hughes Medical Institute

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2015
Publication Date: 2/13/2016
Citation: Li, K., Hegarty, J., Zhang, C., Wan, A., Wu, J., Brown Guedira, G.L., Chen, X., Munoz-Amatriain, M., Fu, D., Dubcovsky, J. 2016. Fine mapping of barley locus Rps6 conferring resistance to wheat stripe rust. Theoretical and Applied Genetics. 129(4):845-859.

Interpretive Summary: Wheat stripe rust is a major disease of wheat that is causing large economic losses in many wheat-growing regions of the world. Deployment of stripe rust resistance genes has been an effective strategy for controlling this pathogen, but many of these genes have been defeated by new stripe rust races. By contrast, genes providing resistance to this wheat pathogen in other grass species (nonhost resistance) have been effective for long periods of time. Barley varieties are predominately immune to wheat stripe rust, but we identified three accessions of wild barley that are susceptible to this pathogen. Using these accessions, we mapped a barley locus conferring resistance on chromosome arm 7H and designated it as Rps6. The detection of the same locus in the cultivated barley ‘Tamalpais’ and in the Chinese barley ‘Y12’ suggests that Rps6 may be a frequent component of barley resistance to stripe rust. Using a high density mapping population we precisely mapped Rps6. Since no candidate resistance genes were identified, a dedicated positional cloning effort in barley will be required to identify Rps6. The identification of this and other barley genes conferring resistance to stripe rust can contribute to our understanding of the mechanisms for durable resistance against this devastating wheat pathogen.

Technical Abstract: Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a major disease of wheat that is causing large economic losses in many wheat-growing regions of the world. Deployment of Pst resistance genes has been an effective strategy for controlling this pathogen, but many of these genes have been defeated by new Pst races. By contrast, genes providing resistance to this wheat pathogen in other grass species (nonhost resistance) have been effective for long periods of time. Barley varieties (Hordeum vulgare ssp. vulgare) are predominately immune to wheat Pst, but we identified three accessions of wild barley (Hordeum vulgare ssp. spontaneum) that are susceptible to this pathogen. Using these accessions, we mapped a barley locus conferring resistance to Pst on the distal region of chromosome arm 7HL and designated it as Rps6. The detection of the same locus in the cultivated barley ‘Tamalpais’ and in the Chinese barley ‘Y12’ by allelism test suggests that Rps6 may be a frequent component of barley intermediate host resistance to Pst. Using a high density mapping population (>10,000 gametes) we precisely mapped Rps6 within a 0.06 cM region that is colinear to regions in Brachypodium (93.8 kb) and rice (9.7 kb). Since no candidate genes were identified in these colinear regions, a dedicated positional cloning effort in barley will be required to identify Rps6. The identification of this and other barley genes conferring resistance to Pst can contribute to our understanding of the mechanisms for durable resistance against this devastating wheat pathogen.