Identification of resistance to Pseudocercosporella herpotrichoides in Triticum monococcum

Eyespot is an important disease of wheat in the United States Pacific Northwest. Genes Pch1, located on chromosome 7D, and Pch2, located on chromosome 7A, are the only known sources of eyespot resistance in hexaploid wheat. A core collection of Triticum monococcum, a close relative of the A-genome donor of bread wheat, consisting of 118 accessions from 26 countries was screened for resistance using a beta-glucuronidase-transformed strain of the pathogen. Fifty-two (44%) accessions from 15 different countries were resistant. More than half of the accessions collected in Turkey (26 of 42) were resistant. Two accessions were more resistant than resistant cultivars Cappelle Desprez (Pch2) and Madsen (Pch1). Screening these accessions for the isozyme marker Ep-A1b, which is linked with Pch2 in hexaploid wheat, revealed variation but no association with resistance. These results indicate T. monococcum is a new source of resistance to Pseudocercosporella herpotrichoides that potentially contains more effective resistance to P. herpotrichoides than that conferred by either Pch1 or Pch2.