|VALENTINI, GISELI - Universidade Estadual De Maringá|
|GILIO, THIAGO - Universidade Estadual De Maringá|
|MARTINS, ALEXANDRE - Coordenaao De Aperfeioamento De Pessoal De Nivel Superior|
|Pastor Corrales, Marcial - Talo|
Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2016
Publication Date: 12/27/2016
Citation: Hurtado-Gonzales, O.P., Valentini, G., Gilio, T., Martins, A., Song, Q., Pastor Corrales, M.A. 2016. Fine mapping of Ur-3, a historically important rust resistance locus in common bean. G3, Genes/Genomes/Genetics. 7(2):557-569.
Interpretive Summary: Bean rust is a very destructive disease of dry and snap beans in the United States, Latin America, and Africa. We have used a new approach involving traditional and next generation sequencing technologies to identify a molecular marker that tags effectively the historically important Ur-3 gene that confers resistance to the bean rust disease. Previous published molecular marker tagging the Ur-3 gene produced false results when used in the development of dry and snap beans with the Ur-3 gene. The new marker accurately identifies dry and snap bean plants having the Ur-3 gene alone and in combination with other rust resistance genes. Therefore, this marker will be most useful for the development of beans combining Ur-3 and other rust genes that will provide broad resistance to the highly variable rust pathogen. In addition, the utilization of the new molecular marker will reduce significantly the time and labor associated with the transfer of the Ur-3 gene using inoculations of bean plants with specific strains of the rust pathogen. Moreover, the new approach used in this study could be used to develop effective molecular markers for genes conferring resistance to other fungal pathogens of common bean.
Technical Abstract: Resistance in common bean to the highly variable bean rust pathogen is conditioned by single and dominant genes. The Ur-3 gene confers resistance to 55 of 94 races of this pathogen maintained at Beltsville, MD, Ur-3 is also resistant to many races that overcome all other rust resistance genes in common bean. Since 1978, when Ur-3 was first reported, this gene has been used extensively as a source of resistance in numerous dry and snap bean varieties in the United States and other nations. Despite the current and historical importance of Ur-3, there are no reliable molecular markers to tag this gene for marker assisted selection. In this study, we positioned the Ur-3 locus in a 46.5 kb genomic region of chromosome Pv11 based on the analyses of recombinant inbred lines and cultivars genotyped with BARCBEAN6K_3 BeadChip, SSR and KASP markers. We discovered a KASP marker SS68 that is tightly linked to the Ur-3 locus. Validation of SS68 on a panel of 130 diverse common bean lines and varieties revealed that SS68 was extremely accurate and it did not produce false results. We identified six annotated candidate genes in the delimited genomic region of the Ur-3 locus. The SS68 marker will be of great value to pyramid Ur-3 with other rust resistance genes. This is the first time that a fine mapping approach has been used to discover markers linked to a rust resistance locus in common bean.