Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Proceedings
Publication Acceptance Date: October 1, 2005
Publication Date: February 1, 2006
Citation: Miklas, P.N. 2006. Molecular advances with common bean rust resistance. Bean Improvement Cooperative Annual Report. 49:47-48. Technical Abstract: Bean rust is a serious fungal disease that limits common bean (Phaseolus vulgaris L.) production worldwide. The disease can be adequately controlled by genetic resistance in the host. For bean rust, as with most host/hypervariable pathogen interactions, co-evolution of numerous resistance genes and pathotypes has transpired. Nine named Ur-3, Ur-4, Ur-5, Ur-6, Ur-7, Ur-9, Ur-11, Ur-12, and Ur-13, and four undefined rust resistance genes: one from BAC 6; one from Ouro Negro; and two from Dorado, have all been tagged with RAPD or SCAR markers and placed on the genetic linkage map. Twelve of the R genes map to five linkage groups. Although numerous markers are available for indirect selection and to facilitate development of resistance gene pyramids, few actual applications of MAS in breeding for rust resistance have been published, perhaps due to relative ease of direct screening with the pathogen. The occurrence of false positives and negatives, where the coupling (cis) marker is present but the gene is absent, or vice versa, has also limited implementation of MAS. The comprehensive linkage map of the rust resistance genes could be used to direct allelism tests for characterization and naming of new rust resistance genes.