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Recombination between a Crown Rust Resistance Locus and an Interchange Breakpoint in Hexaploid Oat
Author(s) -
Wilson W. F.,
McMullen M. S.
Publication year - 1997
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1997.0011183x003700060003x
Subject(s) - locus (genetics) , biology , breakpoint , genetics , recombination , allele , chromosome , gene
The oat ( Avena sativa L.) cultivars, Steele and Dumont, differ by a chromosomein terchange. Twot ightly linked or allelic crown rust resistance genes ( Pc‐63 and Pc‐38 ) are located on one of the segments involved in the interchange. Recombinant chromosomes can result from crossing‐over in the region between the crown rust resistance locus and the interchange breakpoint. Our objectives were to use a diallelic duplicate locus to (i) identify recombinant BC 1 F 1 genotypes with Pc‐63 in the interchanged position, (it) estimate the linkage relationship between the crown rust resistance locus and the interchange breakpoint, and (iii) recover duplication genotypes that possess four copies of Pc‐63 . Segregation of BC 1 F 2 families was used to detect recombination within an interchanged chromosome segment in F 1 interchange heterozygotes. Only 3/7 of the single crossover recombinant gametes could be recognized by duplicate dominant segregation in BC 1 F 2 families. After inoculation of 145 BC 1 F 2 families with a crown rust ( Puccinia coronata Corda var. avenae W.P. Fraser & Ledingham) isolate avirulent on Pc‐63 and virulent on Pc‐38 , we identified 11 recombinant families segregating 15R:1S. A 15:1 segregation ratio indicated Pc‐63 recombined to an interchanged position as a result of crossing‐over between the crown rust resistance locus and the interchange breakpoint. Our data indicated Pc‐63 was linked in repulsion and distal to the interchange breakpoint with 17.7% recombination observed between the crown rust resistance locus and the breakpoint. Testcross segregation ratios confirmed that recombination occurred and allowed identification of a true breeding duplication genotype that possessed four copies of Pc‐63 . Increasing the dosage of Pc‐63 did not alter the expected infection type conferred by a one or two copies of Pc‐63 .