Monday, 7 November 2005
8

Linkage Relationships among Factors That Affect Groat Oil Concentration, Crown Rust Resistance, Stem Rust Resistance and Multifloret Character in Oat.

Diego Vilaro and Michael McMullen. North Dakota State University, Loftsgard Hall, Fargo, ND 58105

Crown rust resistance (CRR) conferred by a source designated IAB is apparently controlled by a single dominant gene. Observations of breeding populations suggest IAB resistance is associated with low groat oil concentration. Stem rust resistance (SRR) conferred by a source designated ‘pg-a complex', is conferred by at least two recessive genes. Lines with pg-a and IAB in the homozygous condition have not been identified in breeding populations, which suggests that IAB resistance is associated with one of the components of pg-a complex. A component of pg-a stem rust resistance in the naked cultivar ‘Paul' appears to be associated with a gene conferring the multifloret or naked character. The naked character and the multiflorous spikelet always occur together, and in Paul a single dominant gene confers this trait. The overall objective of this project is to genetically describe these relationships. Three F2 populations from the CR susceptible/resistant ‘Otana'/'Morton' cross were evaluated for resistance to an isolate comprised of prevalent crown rust races in North Dakota. IAB CRR was conferred by one dominant gene and one suppressor gene as the 13:3 ratio indicated. Testcrosses were obtained involving the pg-a SRR line ND873126 and Morton to describe the association between IAB and pg-a hypothesized as being in repulsion. Morton and ND873126 differ by a single factor relative to resistance conferred by pg-a. BC1F2 families from this cross suggested strong linkage of CRR and SRR factors. The relationship between CRR from the IAB source and oil concentration was evaluated in a field experiment involving 33 F5:6 lines with and without crown rust resistance. Interaction between lines and oil concentration was detected, however IAB and low oil concentration were not significantly associated. The information from this project will allow useful combination of these traits in the oat breeding program.

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