Comparison of a modified assay method for the endopeptidase marker Ep-D1b with the Sequence Tag Site marker XustSSR2001–7DL for strawbreaker foot rot resistance in wheat

The endopeptidase marker Ep‐D1b and Sequence Tag Site (STS) marker XustSSR2001–7DL were reported to be closely associated with the most effective resistance gene (Pch1) in wheat (Triticum aestivum L.) for strawbreaker foot rot Pseudocercosporella herpotrichoides (Fron) Deighton]. Our objectives were to: (i) develop an efficient assay method for Ep‐D1b in wheat; (ii) correlate endopeptidase zymograms to strawbreaker foot rot reactions of various wheat genotypes; and (iii) compare the utility of Ep‐D1b and XustSSR2001–7DL for predicting disease response. An improved method of assaying for the Ep‐D1b marker using roots from a single seedling was developed, which is a 2.5‐fold improvement over the previous method. Thirty‐eight wheat genotypes with known reactions to strawbreaker foot rot were analysed for Ep‐D1b and the STS marker. Six distinct endopeptidase zymograms were identified among these 38 genotypes tested, and three of these patterns were novel. The endopeptidase marker was 100% accurate for predicting strawbreaker foot rot disease response, whereas the STS marker predicted the correct phenotype with approximately 90% accuracy. The endopeptidase marker Ep‐D1b was more effective and was more economical for use in marker‐assisted selection strategies for Pch1 in our laboratory compared with the STS marker.