Submitted to: Agronomy Abstracts
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2003
Publication Date: 11/3/2003
Citation: Hoffman, D.L., Chong, J. 2003. The Identification and Mapping of a Crown Rust Resistance Gene Block in Oat. In Annual Meetings Abstracts [CD-ROM]. ASA, CSSA, and SSSA, Madison, WI. Interpretive Summary: Crown rust is a devastating disease of oat and other grasses. Host plant resistance is currently the most effective means for controlling the disease. Many resistance genes have been identified in oat although many of these genes have been readily made ineffectual by the mutating rust pathogen. In some cases, what was thought as one resistance gene turned out to be a complex of several genes that may be a more durable resistance if all of the genes are transferred in the breeding process. This study was conducted to see if a previously determined resistance gene (Pc-58) is really to due one gene or possibly more.. Inbred lines of a mapping population were individually infected with three races of the crown rust fungus known to affect Pc-58 to further genetically investigate this gene. It was found that Pc-58 was actually a block of five linked genes that linked to markers on an oat map. With these markers and their derivatives, the genes of this block could be combined with other resistance genes including slow rusting genes to make a more durable resistance to the destructive crown rust pathogen of oat.
Technical Abstract: Genetic resistance is the most effective method to control crown rust (causal agent: Puccinia coronata f.sp. avenae), a devastating disease of oat (Avena sativa). 'TAM O-301', released by Texas A&M in the 1970's, has effective crown rust resistance, subsequently named Pc-58. The objectives of this study were to determine the mode of inheritance of Pc-58 in a F6:7 'Ogle' x TAM O-301 recombinant inbred (RI) population, to identify RFLP markers linked to this resistance, and to map the Pc-58 resistance in a molecular linkage map developed from this RI population. Segregation for Pc-58 resistance in the RI population was tested with three crown rust pathotypes, all avirulent on TAM O-301 and virulent on Ogle. Genetic analyses of the segregation data to the three pathotypes indicated that the Pc-58 resistance was conditioned by five linked loci, rather than a single locus as previously thought. The resistance loci were linked to the ends of two linkage groups, OT 32 and OT 33, in the Ogle x TAM O-301 map. Several RFLP markers were found to flank the Pc-58 rust resistance gene block. It was concluded that conversion of these markers to PCR-based markers, plus the identification of new PCR markers inside the resistance block, would facilitate pyramiding of these linked genes along with other effective crown rust resistance genes into elite oat backgrounds.