Submitted to: Bean Improvement Cooperative Proceedings
Publication Type: Trade Journal
Publication Acceptance Date: December 30, 2006
Publication Date: December 30, 2006
Citation: Pastor Corrales, M.A. 2006. Diversity of the rust pathogen and common bean guides gene deployment for development of bean cultivars with durable rust resistance. Bean Improvement Cooperative Proceedings. 49:51-52.
A sound approach for the development of common bean cultivars with durable rust resistance requires a comprehensive understanding of the great diversity of the bean rust pathogen and how this diversity affects each of the available rust resistance genes. Our virulence diversity studies of Uromyces appendiculatus show that rust resistance genes from Andean beans tend to be susceptible to Andean races of the rust pathogen. However, these genes are often very effective against many Middle American races. Conversely, the rust resistance genes from Middle American beans often have broad resistance, but are susceptible to many Middle American races and particularly resistant to most Andean races. The Middle American rust resistance gene known as Ur-11 is resistant to all known races of the rust pathogen except race 108 which is of Middle American origin. On the other hand, the Andean Ur-4 rust resistance gene is susceptible to most Andean races of the rust pathogen but it is resistant to race 108 and to many other Middle American races. The Ur-3 and Ur-5 rust resistance genes of Middle American origin are susceptible to several Middle American races of the rust fungus but they provide resistance to most Andean races. Therefore, a practical consequence of the bean-rust diversity and coevolution studies is the realization that combining selected rust resistance genes (gene pyramiding) from Andean and Middle American gene pools could result in bean cultivars with effective and durable rust resistance throughout the world. We have developed great northern and five pinto bean germplasm lines that are unique in the world for the genes they combine. They have two Middle American (Ur-3 and Ur-11) and two Andean (Ur-4 and Ur-6) genes and they are resistant to all known races of U. appendiculatus under greenhouse conditions and are resistant in the USA, South Africa and Honduras under field conditions.