Maccarone L D, Barbetti M J, Sivasithamparam K, Jones R A C
School of Plant Biology, Faculty of Natural and Agricultural Sciences, University of Western Australia, Stirling Highway, Crawley, WA 6009.
School of Plant Biology, Faculty of Natural and Agricultural Sciences, University of Western Australia, Stirling Highway, Crawley, WA 6009, and Agricultural Research Western Australia, Department of Agriculture and Food, Locked Bag No. 4, Bentley Delivery Centre, WA 6983.
Plant Dis. 2010 May;94(5):563-569. doi: 10.1094/PDIS-94-5-0563.
Lettuce plants showing symptoms of lettuce big-vein disease were collected from fields in the Perth Metropolitan region of southwest Australia. When root extracts from each plant were tested by polymerase chain reaction (PCR) using primers specific to the rDNA internal transcribed spacer (ITS) region of Olpidium brassicae and O. virulentus, only O. virulentus was detected in each of them. The nucleotide sequences of the complete rDNA ITS regions of isolates from five of the root samples and 10 isolates of O. virulentus from Europe and Japan showed 97.9 to 100% identities. However, with the six O. brassicae isolates, their identities were only 76.9 to 79.4%. On phylogenetic analysis of the complete rDNA-ITS region sequences of the five Australian isolates and 10 others, the Australian isolates fitted within two clades of O. virulentus (I and II), and within clade I into two of its four subclades (Ia and Id). Japanese isolates had greatest sequence diversity fitting into both clades and into all of clade I subclades except Ib, while European isolates were restricted to subclades Ib and Id. When the partial rDNA-ITS region sequences of two additional southwest Australian isolates, four from Europe, and four from the Americas were included in the analyses, the Australian isolates were within O. virulentus subclades Ia and Id, the European isolates within subclade Ic, and the American isolates within subclades Ia and Ib. These findings suggest that there may have been at least three separate introductions of O. virulentus into the isolated Australian continent since plant cultivation was introduced following its colonization by Europeans. They also have implications regarding numbers of different introductions to other isolated regions. Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus were both detected when symptomatic lettuce leaf tissue samples corresponding to the root samples from southwest Australia were tested using virus-specific primers in reverse transcription-PCR, so presence of both viruses was associated with O. virulentus occurrence.
从澳大利亚西南部珀斯都会区的农田中采集了表现出生菜大脉病症状的生菜植株。当使用针对芸薹油壶菌和致病油壶菌核糖体DNA内转录间隔区（ITS）区域的引物，通过聚合酶链反应（PCR）对每株植物的根提取物进行检测时，在每株植物中仅检测到致病油壶菌。来自五个根样本的分离株以及来自欧洲和日本的10个致病油壶菌分离株的完整核糖体DNA ITS区域的核苷酸序列显示出97.9%至100%的同一性。然而，对于六个芸薹油壶菌分离株，它们的同一性仅为76.9%至79.4%。对五个澳大利亚分离株和其他10个分离株的完整核糖体DNA-ITS区域序列进行系统发育分析时，澳大利亚分离株归入致病油壶菌的两个进化枝（I和II），在进化枝I中又归入其四个亚进化枝中的两个（Ia和Id）。日本分离株具有最大的序列多样性，归入两个进化枝以及进化枝I除Ib之外的所有亚进化枝，而欧洲分离株仅限于亚进化枝Ib和Id。当将另外两个澳大利亚西南部分离株、四个欧洲分离株和四个美洲分离株的部分核糖体DNA-ITS区域序列纳入分析时，澳大利亚分离株在致病油壶菌亚进化枝Ia和Id内，欧洲分离株在亚进化枝Ic内，美洲分离株在亚进化枝Ia和Ib内。这些发现表明，自欧洲人殖民后引入植物种植以来，致病油壶菌可能至少有三次分别传入孤立的澳大利亚大陆。它们对于其他孤立地区不同引入次数也具有启示意义。当使用病毒特异性引物通过逆转录-PCR对与澳大利亚西南部根样本相对应的有症状生菜叶片组织样本进行检测时，检测到了生菜大脉相关病毒和米拉弗洛里生菜大脉病毒，因此这两种病毒的存在都与致病油壶菌的发生有关。
