Identification of a candidate gene for the wheat endopeptidase Ep-D1 locus and two other STS markers linked to the eyespot resistance gene Pch1
Identification of a candidate gene for the wheat endopeptidase Ep-D1 locus and two other STS markers linked to the eyespot resistance gene Pch1
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DOI：
10.1007/s00122-007-0664-4
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发表时间：
2008-01-01
影响因子：
5.4
通讯作者：
Riera-Lizarazu, Oscar
中科院分区：
文献类型：
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作者：
Leonard, Jeffery M.;Watson, Christy J. W.;Riera-Lizarazu, Oscar
小麦容易发生秸秆腐烂病（眼斑病），这是一种由 Oculimacula yallundae 和 O. acuformis 引起的真菌病害。最有效的遗传抗性来源是 Pch1，一种源自山羊草的基因。与 Pch1 连锁的内肽酶同工酶标记等位基因 Ep-D1b 已被证明比迄今为止开发的基于 DNA 的标记更能有效地追踪耐药性。因此，我们试图鉴定 Ep-D1 的候选基因作为基于 DNA 的标记的基础。比较作图表明内肽酶基因座 Ep-D1（小麦）、enp1（玉米）和 Enp（水稻）是直系同源的。由于玉米内肽酶基因座 enp1 的产物已被证明表现出与从大肠杆菌中纯化的寡肽酶 B 相似的生化特性，因此我们推断 Ep-D1 也可能编码寡肽酶 B。与此假设一致，源自编码小麦表达序列标签 (EST) 的寡肽酶 B 的序列标记位点 (STS) 标记 Xorw1 显示与 Ep-D1 完全连锁，并且源自小麦品种 Coda 和 Brundage 杂交的 254 个重组自交系 (RIL) 群体中的 Pch1。另外两个 STS 标记 Xorw5 和 Xorw6 以及三个微卫星标记（Xwmc14、Xbarc97 和 Xcfd175）也与 Pch1 完全连锁。另一方面，Xwmc14、Xbarc97 和 Xcfd175 在 W7984 x Opata85 RIL 群体中显示重组，表明在 Coda/Brundage 群体中 Pch1 附近的重组减少。在一组具有已知眼斑反应的 44 个小麦品种中，Xorw1、Xorw5 和 Xorw6 在预测 Pch1 是否存在方面准确度为 100%，而 Xwmc14、Xbarc97 和 Xcfd175 的效果较差。因此，连锁作图和种质调查表明，此处鉴定的 STS 标记应可用于 Pch1 的间接选择。
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.