PAG-XV  Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA


P339 : Wheat, Barley, Rye, Oat, and related

Fine Scale Mapping Of The Strawbreaker Foot Rot Resistant Gene Pch1 And Identification Of A Candidate Gene For The Endopeptidase Ep-D1 Locus

Jeffrey M. Leonard1 , Christy J. W. Watson1 , Arron Carter2 , Jenny L. Hansen2 , Kimberley G. Campbell3 , Robert S. Zemetra2 , Oscar Riera-Lizarazu1

1  Department of Crop and Soil Science, Oregon State University, Corvallis, OR, 97331
2  Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844
3  USDA-ARS Wheat Genetics, Quality, Physiology, and Disease Research Unit, WSU, Pullman WA 99164

Strawbreaker footrot or eyespot is an important fungal disease of wheat caused by Pseudocercosporella herpotrichoides.
The most effective source of genetic eyespot resistance is provided by Pch1, a gene derived from Aegilops ventricosa. An endopeptidase-based isozyme marker, Ep-D1b, is tightly linked to Pch1 and has been used effectively for marker-assisted selection. A more utilitarian AFLP-derived marker, XustSSR2001 has been developed. However, it is not sufficiently linked to Pch1 to guarantee selection of disease-resistant phenotypes.
This study encompassed two objectives; 1) to develop a PCR marker for the Ep-D1 locus, and 2) to generate a dense genetic map of chromosome 7D in the Pch1 region. A genetic linkage map was built using 257 recombinant inbred lines derived from a cross between eyespot resistant line ‘Coda’ and eyespot sensitive line ‘Brundage’. The Ep-D1b isozyme marker segregated perfectly with the disease resistant phenotype. A PCR marker (Xorw1) that was designed from an EST with homology to a peptidase was also completely linked to Pch1 making it a likely candidate for the Ep-D1b locus. Based upon synteny with rice, we developed two other EST-derived markers which were also completely linked to disease resistance in the mapping population. The association of these markers was verified in a panel of 21 lines with Pch1 and 24 lines without Pch1.