IDENTIFICATION OF ISOLATE SPECIFIC SOURCES OF SCALD RESISTANCE IN TURKISH BARLEY (HORDEUM-VULGARE) ACCESSIONS

Disease reactions to specific Rhynchosporium secalis isolates from wes tern Canada were characterized on forty Turkish Hordeum vulgare access ions. One accession, MEH151-1, exhibited resistance against isolate WR S1860 and was also resistant to isolates WRS1493 and WRS1824 which wer e avirulent to the Rh gene. A related line, MEH151-2 exhibited resista nce to WRS1493 but not to WRS1860. Crosses between both MEH15I-1 and M EH151-2, and the susceptible cultivar, Harrington, were used to demons trate a linkage between resistance to WRS1493 and an allele specific a mplicon, Falc666. Resistance to WRS1860 imparted by MEH1S1-1 was mappe d to the other side of the Falc666 locus. Falc666 was previously shown to be located near the centromere on the long arm of chromosome 3. Ch aracterization of the genetic basis for the scald resistance phenotype exhibited by these Turkish accessions, coupled with the identificatio n of marker linkages, provides evidence for genetic variation in scald resistance in this chromosomal region.