Diagnostic value of molecular markers linked to the eyespot resistance gene Pch1 in wheat

Eyespot is a major disease of common wheat (Triticum aestivum L.) in temperate climates and causes yield losses of up to 40%. The causal agents of eyespot are Oculimacula acuformis (syn. Tapesia acuformis; anamorph: Helgardia acuformis syn. Pseudocercosporella herpotrichoides var. acuformis) and O. yallundae (syn. T. yallundae; anamorph: H. yallundae syn. P. h. var. herpotrichoides). Pch1 located on chromosome 7DL is the most important and most effective resistance gene, but its use in practical breeding is limited because of difficulties in phenotyping and the fact that markers like XustSSR2001-7DL are often population-specific in German wheat cultivars. Therefore, based on results obtained for endopeptidase Ep-D1a, which is very closely linked to Pch1, molecular markers located in the terminal region of chromosome 7DL were analysed in three DH (double haploid) populations. In a next step these molecular markers were validated on a set of German winter wheat cultivars to obtain information on their usefulness for marker assisted selection (MAS). Based on the analysis of 127 DH-lines, linkage to Pch1 (Ep-D1) was obtained for Xorw1, Xorw5, Xorw6, Xcfd175, Xbarc76, Xwmc14, and Xcfa2040. Analyses of 104 German winter wheat cultivars showed that Xorw1, Xorw6 and the SSR Xcfd175 of these markers are well suited for MAS in German wheat breeding.