Li Y P, Wright D G, Lanoiselet V, Wang C P, Eyres N, Real D, You M P, Barbetti M J
School of Plant Biology, The University of Western Australia, Crawley W.A. 6009 Australia.
Department of Agriculture and Food Western Australia, Baron-Hay Court, South Perth, W.A. 6151, Australia.
Plant Dis. 2012 May;96(5):769. doi: 10.1094/PDIS-12-11-1040-PDN.
Tedera (Bituminaria bituminosa (L.) C.H. Stirton var. albomarginata) has been successfully established across the mixed-farming (wheat-sheep) region of Western Australia because this species has remarkable drought tolerance and can survive the dry-summer period with strong retention of green leaf. A leaf spot symptom involving pale brown lesions with distinct dark brown margins had been observed in genetic evaluation plots of tedera at Medina and Mount Barker, Western Australia, and a Phoma sp. was isolated. Single-spore isolations of a typical Phoma sp. isolate were made onto potato dextrose agar and maintained at 20°C, and a representative culture has been lodged in the Western Australian Culture Collection Herbarium maintained at the Department of Agriculture and Food Western Australia (Accession No. WAC13435). Amplification of the internal transcribed spacer (ITS) 1 and ITS2 regions flanking the 5.8S rRNA gene were carried out with universal primers ITS1 and ITS4 according to published protocol (3). The DNA PCR products were sequenced and BLAST analyses was used to compare sequences with those in GenBank. The sequence had 99% nucleotide identity with the corresponding sequence in GenBank for Phoma herbarum. Isolates also showed morphological (e.g., 1) and molecular (e.g., 2) similarities with P. herbarum as described in other reports. The relevant sequence information for a representative isolate has been lodged in GenBank (Accession No. JQ282910). A conidial suspension of 10 conidia ml from a single-spore culture was spray inoculated onto foliage of 6-week-old tedera plants maintained under >90% relative humidity conditions for 72-h postinoculation. Symptoms evident by 10 days postinoculation consisted of pale brown lesions, mostly 1.5 to 4 mm in diameter, which developed a distinct, dark brown margin. Occasional lesions also showed a distinct chlorotic halo extending 1 to 1.5 mm outside the boundary of the lesion. Infection studies were successfully repeated twice and P. herbarum was readily reisolated from infected foliage. No disease was observed on and no P. herbarum were isolated from water-inoculated control plants. Except for a recent published report of P. herbarum on field pea (Pisum sativum L.) (2), this pathogen has only been noted in the Australian Plant Pest Database as occurring on lucerne (Medicago sativa L.) and soybean (Glycine max (L.) Merr.) in Western Australia in 1985 and on a Protea sp. in 1991. To our knowledge, this is the first published report of P. herbarum as a pathogen on tedera in Australia or elsewhere. That P. herbarum occurs on other hosts in Australia and has a wide host range elsewhere together suggest its potential to be a pathogen on a wider range of host genera and species. References: (1) G. L. Kinsey. No. 1501 in: IMI Descriptions of Fungi and Bacteria. 2002. (2) Y. P. Li et al. Plant Dis. 95:1590, 2011. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.
泰德拉（Bituminaria bituminosa (L.) C.H. Stirton var. albomarginata）已在西澳大利亚的混合作物种植区（小麦-绵羊养殖区）成功种植，因为该物种具有显著的耐旱性，在夏旱期能保持绿叶，从而存活下来。在西澳大利亚梅迪纳和巴克山的泰德拉遗传评估试验田中，观察到一种叶斑症状，病斑呈浅褐色，边缘深褐色明显，并且分离出了一种茎点霉属真菌。将典型的茎点霉属真菌分离株进行单孢分离，接种到马铃薯葡萄糖琼脂培养基上，在20°C下保存，一份代表性培养物保存在西澳大利亚农业与食品部的西澳大利亚培养物保藏中心标本馆（保藏编号WAC13435）。根据已发表的方案(3)，使用通用引物ITS1和ITS4对5.8S rRNA基因两侧的内转录间隔区（ITS）1和ITS2区域进行扩增。对DNA PCR产物进行测序，并使用BLAST分析将序列与GenBank中的序列进行比较。该序列与GenBank中草本茎点霉的相应序列具有99%的核苷酸同一性。如其他报告所述，分离株在形态学（如1）和分子学（如2）上也与草本茎点霉相似。一份代表性分离株的相关序列信息已保存在GenBank（保藏编号JQ282910）。将来自单孢培养物的浓度为每毫升10个分生孢子的分生孢子悬浮液喷雾接种到6周龄的泰德拉植株叶片上，接种后在相对湿度>90%的条件下保持72小时。接种后10天出现的症状为浅褐色病斑，大多直径为1.5至4毫米，病斑边缘深褐色明显。偶尔的病斑还显示出明显的褪绿晕圈，在病斑边界外延伸1至1.5毫米。感染研究成功重复了两次，并且很容易从感染的叶片中再次分离出草本茎点霉。在水接种的对照植株上未观察到病害，也未分离出草本茎点霉。除了最近一篇关于草本茎点霉侵染豌豆（Pisum sativum L.）的报道(2)外，该病原菌仅在澳大利亚植物害虫数据库中被记录于1985年出现在西澳大利亚的苜蓿（Medicago sativa L.）和大豆（Glycine max (L.) Merr.）上，以及1991年出现在一种山龙眼属植物上。据我们所知，这是草本茎点霉作为泰德拉病原菌在澳大利亚或其他地方的首次公开报道。草本茎点霉在澳大利亚寄生于其他寄主，在其他地方寄主范围广泛，这表明它有可能成为更广泛寄主属和种的病原菌。参考文献：(1) G. L. Kinsey. 《IMI真菌与细菌描述》第1501号。2002年。(2) Y. P. Li等人。《植物病害》95:1590，2011年。(3) T. J. White等人。《PCR方案：方法与应用指南》第315页。学术出版社，加利福尼亚州圣地亚哥，1990年。
