Identification of a candidate gene for the wheat endopeptidase Ep-D1 locus and two other STS markers linked to the eyespot resistance gene Pch1

• Published in: Theoretical and applied genetics Vol. 116; no. 2; pp. 261 - 270
• Main Authors: Leonard, Jeffrey M, Watson, Christy J. W, Carter, Arron H, Hansen, Jennifer L, Zemetra, Robert S, Santra, Dipak K, Campbell, Kimberly G, Riera-Lizarazu, Oscar
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 2008; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Aegilops ventricosa; Agriculture; Ascomycota; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Chromosome Mapping; Classical genetics, quantitative genetics, hybrids; Crosses, Genetic; DNA Primers - genetics; Endopeptidases - genetics; Escherichia coli; Fundamental and applied biological sciences. Psychology; Genetic Markers - genetics; Genetics of eukaryotes. Biological and molecular evolution; Immunity, Innate - genetics; Life Sciences; Microsatellite Repeats - genetics; Original Paper; Oryza sativa; Plant Biochemistry; Plant Breeding/Biotechnology; Plant Diseases - microbiology; Plant Genetics and Genomics; Pteridophyta, spermatophyta; Sequence Tagged Sites; Triticum - enzymology; Triticum - genetics; Triticum aestivum; Vegetals; Zea mays; Leaf Sheath; Association Panel; International Triticeae Mapping Initiative Population; International Triticeae Mapping Initiative; Endopeptidase; Monocotyledones; Enzyme; Identification; Resistance; Peptidases; Gramineae; Angiospermae; Hydrolases; Genetics; Spermatophyta; Agriculture; Candidate gene; Locus; Triticum aestivum
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-007-0664-4

Wheat is prone to strawbreaker foot rot (eyespot), a fungal disease caused by Oculimacula yallundae and O. acuformis. The most effective source of genetic resistance is Pch1, a gene derived from Aegilops ventricosa. The endopeptidase isozyme marker allele Ep-D1b, linked to Pch1, has been shown to be more effective for tracking resistance than DNA-based markers developed to date. Therefore, we sought to identify a candidate gene for Ep-D1 as a basis for a DNA-based marker. Comparative mapping suggested that the endopeptidase loci Ep-D1 (wheat), enp1 (maize), and Enp (rice) were orthologous. Since the product of the maize endopeptidase locus enp1 has been shown to exhibit biochemical properties similar to oligopeptidase B purified from E. coli, we reasoned that Ep-D1 may also encode an oligopeptidase B. Consistent with this hypothesis, a sequence-tagged-site (STS) marker, Xorw1, derived from an oligopeptidase B-encoding wheat expressed-sequence-tag (EST) showed complete linkage with Ep-D1 and Pch1 in a population of 254 recombinant inbred lines (RILs) derived from a cross between wheat cultivars Coda and Brundage. Two other STS markers, Xorw5 and Xorw6, and three microsatellite markers (Xwmc14, Xbarc97, and Xcfd175) were also completely linked to Pch1. On the other hand, Xwmc14, Xbarc97, and Xcfd175 showed recombination in the W7984 x Opata85 RIL population suggesting that recombination near Pch1 is reduced in the Coda/Brundage population. In a panel of 44 wheat varieties with known eyespot reactions, Xorw1, Xorw5, and Xorw6 were 100% accurate in predicting the presence or absence of Pch1 whereas Xwmc14, Xbarc97, and Xcfd175 were less effective. Thus, linkage mapping and a germplasm survey suggest that the STS markers identified here should be useful for indirect selection of Pch1.