RUST RESISTANT BEAN GERMPLASM RELEASES, 1994-1996

Authors: Stavely, J; KELLY, J - MI ST UNIV E LANSING MI; GRAFTON, K - ND STATE UNIV FARGO ND; MULLINS, C - TN EXPT STN CROSSVILE TN; STRAW, ALLEN - TN EXPT STN CROSSVILLE TN; MCMILLAN, R - FL EXPT STN HOMESTEAD FL; BEAVER, J - PR EXPT STN MAYAGUEZ PR; MIKLAS, P - 5354-10-00; STEINKE, J - NJ EXPT STN BRIDGETON NJ; STEADMAN, J - UNIV NE LINCOLN

Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rust disease of common bean causes epidemics that result in crop losses, market instability, and economic hardship to farmers in many bean production areas. Host resistance is the most efficient control, but a high degree of pathogenic variability in the causal fungus makes development of resistance that will be effective over time and distance difficult. Continuous monitoring of collections of bean rust from production areas has led to isolation, identification, and maintainence of 87 pathogenic races of this fungus at Beltsville. This paper reports a race newly found in Honduras that produces a susceptible reaction on most previously-identified, resistant bean introductions. However, resistances from several sources are effective against this race. Reported here are 18 rust resistant germplasm releases from 1994 through 1996 that were developed at Beltsville, cooperatively selected for desirable characteristics in several states, and cooperatively released with the involved states. All of these releases are resistant to 86 of the races of the rust fungus and all of them except one pinto are resistant to the newly identified Honduran race. All of these releases contain the I gene for resistance to common mosaic virus and all five dry bean releases contain additional genes for resistance to all strains of the common mosaic. Three of the snap beans are the first to contain a gene for resistance to the recently-introduced bean golden mosaic virus. These resistant releases are being used by breeders to select resistant cultivars that will reduce pesticide usage and increase production efficiency, reduce losses, and better ensure a stable supply of this important, healthful food that is a major export commodity.

Technical Abstract: Pathogenic variability in Uromyces appendiculatus, the fungus causing bean rust, has been monitored from worldwide rust collections to result in isolation and identification of 87 pathogenic races that are maintained at Beltsville for use in resistant germplasm identification and development. In 1996, the 87th of these races was obtained from Honduras and this race produces a susceptible reaction on most of the bean plant introductions that were resistant to the first 86 races. However, the Ur-3 and Ur-4 genes and an unnamed gene or genes from several cultivars provide resistance to this race. In 1994, 1995, and 1996 18 rust resistant germplasm lines were released, that include three navies, one pinto, one great northern, four yellow snaps, three half runner snaps, and six indeterminate snaps. All are resistant to the first 86 races and all but the pinto to the 87th race. All of these releases are homozygous for the I gene for mosaic resistance. The navies and great northern are homozygous for the bc-3 gene, and the pinto for the bc-2 2 gene to provide resistance to all strains of the common mosaic viruses. The last three indeterminate snaps are the first United States snaps that are homozygous for the bgm-1 gene for resistance to bean golden mosaic virus.