Department of Plant Science, University of Manitoba, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada.
Department of Plant Pathology, Washington State University Mount Vernon NWREC, Mount Vernon, WA 98273-4768, USA.
Int J Mol Sci. 2019 Apr 3;20(7):1668. doi: 10.3390/ijms20071668.
Blackleg (Phoma stem canker) of crucifers is a globally important disease caused by the ascomycete species complex comprising of and . Six blackleg isolates recovered from cv. Mizspoona in the Willamette Valley of Oregon were characterized as based on standard pathogenicity tests and molecular phylogenetic analysis. These isolates were compared to 88 characterized isolates from western Canada, 22 isolates from Australia, and 6 isolates from Idaho, USA using maximum parsimony and distance analysis of phylogenetic trees generated from the ITS rDNA (internal transcribed spacer rDNA) sequence, and the and gene sequences. The isolates derived from collected in Oregon formed a separate subclade based on concatenated gene sequences or a single gene sequence, regardless of the analyses. Pathogenicity tests showed that these isolates failed to infect either resistant or susceptible cultivars, but caused severe symptoms on three cultivars (Accession number: UM1113, UM1112, and UM1161), a var. (cabbage) cultivar (Copenhagen Market), and two cultivars (CBM, a common brown Mustard, and Forge). These findings demonstrated that the isolates derived from a crop in Oregon were genetically distinct from existing species of , and constitute a new subclade, herein proposed as 'americensis'.
十字花科黑胫病（Phoma stem canker）是一种全球性重要病害，由包含 和 的子囊菌种复合体引起。从俄勒冈州威拉米特谷的 cv. Mizspoona 中分离出的 6 个黑胫病分离株，根据标准致病性测试和分子系统发育分析，被鉴定为 。这些分离株与来自加拿大西部的 88 个特征明确的 分离株、来自澳大利亚的 22 个分离株和来自美国爱达荷州的 6 个 分离株进行了比较，采用最大简约法和距离分析对基于 ITS rDNA（内部转录间隔区 rDNA）序列和 、 基因序列生成的系统发育树进行分析。来自俄勒冈州采集的 分离株形成了一个单独的亚分支，无论是基于基因序列的串联还是单个基因序列，均形成一个单独的亚分支。致病性测试表明，这些分离株不能感染抗性或敏感性 品种，但会在三个 品种（注册号：UM1113、UM1112 和 UM1161）、一个 var. （白菜）品种（哥本哈根市场）和两个 品种（CBM，一种常见的褐色芥菜和 Forge）上引起严重症状。这些发现表明，来自俄勒冈州作物的 分离株在遗传上与现有的 物种不同，构成了一个新的亚分支，本文建议将其命名为 'americensis'。
