Mapping and identification of molecular markers for the Pc96 gene
conferring resistance to crown rust in oat
Abstract
Oat crown rust caused by Puccinia coronata Cda f. sp. avenae Erikss
(Pca), is a major constraint to oat (Avena sativa L.) production in many
parts of the globe, with host resistance applied as a common strategy to
curb crown rust epidemics. Combining multiple sources of crown rust
resistance (for example, Pc genes conferring seedling resistance) in a
single genetic background can be expedited by marker-assisted selection
using molecular markers that are tightly linked with resistance loci.
Pc96 is a race-specific crown rust resistance gene originating from
cultivated oat that has been deployed in North American oat breeding
programs. SNP markers linked with Pc96 were identified using multiple
interval mapping with 899 polymorphic SNPs in a recombinant inbred line
population developed from a cross between the oat crown rust
differential known to carry Pc96 and the differential line carrying
Pc54. A single resistance locus was identified on chromosome 7D between
60.4 and 91.6 cM with a peak LOD at 87.3 cM. The resistance locus and
linked SNPs were validated in two additional biparental populations,
Ajay x Pc96 and Pc96 x Kasztan. Genotype state at a combination of two
linked SNPs predicted the absence of Pc96 in a broad group of germplasm
with 5% miss-classification. SNPs that are closely linked to the gene
may be beneficial as PCR-based molecular markers in marker-assisted
selection.