Mapping multiple disease resistance genes using a barley mapping population evaluated in Peru, Mexico, and the USA

Authors: ROSSI, C - OREGON STATE UNIV; CUESTA-MARCOS, A - ZARAGOZA, SPAIN; VALES, I - OREGON STATE UNIV; GOMEZ-PANDO, L - LIMA, PERU; ORJEDA, G - LIMA, PERU; Wise, Roger; SATO, K - OKAYAMA UNIV, JAPAN; HORI, K - OKAYAMA UNIV, JAPAN; CAPETTINI, F - EL BATAN, MEXICO; VIVAR, H - EL BATAN, MEXICO; Chen, Xianming; HAYES, P - OREGON STATE UNIV

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2006
Publication Date: 10/1/2006
Citation: Rossi, C., Cuesta-Marcos, A., Vales, I., Gomez-Pando, L., Orjeda, G., Wise, R.P., Sato, K., Hori, K., Capettini, F., Vivar, H., Chen, X., Hayes, P. 2006. Mapping multiple disease resistance genes using a barley mapping population evaluated in Peru, Mexico, and the USA. Molecular Breeding 18:355-366.

Interpretive Summary: We used a well-characterized barley mapping population to determine if barley stripe rust (BSR) resistance genes mapped in Mexico and the USA were effective against a reported new race in Peru. Essentially the same resistance genes were detected using data from each of the three environments, indicating that these resistance alleles are effective against the spectrum of naturally occurring races at these sites. In addition to the mapping population, we evaluated a germplasm array consisting of lines with different numbers of mapped BSR resistance genes. Rust severity differences on some of the genotypes suggest that there are differences in pathogen virulence between Mexico and Peru locations. The highest levels of resistance in Peru were observed when the qualitative resistance gene was pyramided with quantitative resistance genes. We also used the mapping population to locate genes conferring resistance to barley leaf rust and barley powdery mildew. For mildew we identified resistance genes under field conditions in Peru that are distinct from the Mla resistance that we mapped using specific isolates under controlled conditions. These results demonstrate the long-term utility of a mapping population and a well-characterized germplasm array for mapping and validating genes conferring quantitative and qualitative resistance to multiple pathogens.

Technical Abstract: We used a well-characterized barley mapping population to determine if barley stripe rust (BSR) resistance QTL mapped in Mexico and the USA were effective against a reported new race in Peru. Essentially the same resistance QTL were detected using data from each of the three environments, indicating that these resistance alleles are effective against the spectrum of naturally occurring races at these sites. In addition to the mapping population, we evaluated a germplasm array consisting of lines with different numbers of mapped BSR resistance alleles. A higher BSR disease severity on CI10587, which has a single qualitative resistance gene, in Peru vs. Mexico suggests that there are differences in pathogen virulence between the two locations. Confirmation of a new race in Peru will require characterization using a standard set of differentials, an experiment that is underway. The highest levels of resistance in Peru were observed when the qualitative resistance gene was pyramided with quantitative resistance alleles. We also used the mapping population to locate QTL conferring resistance to barley leaf rust and barley powdery mildew. For mildew we identified resistance QTL under field conditions in Peru that are distinct from the Mla resistance that we mapped using specific isolates under controlled conditions. These results demonstrate the long-term utility of a mapping population and a well-characterized germplasm array for mapping and validating genes conferring quantitative and qualitative resistance to multiple pathogens.