Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstr 8, 37077 Göttingen, Germany.
Appl Microbiol Biotechnol. 2013 May;97(10):4467-83. doi: 10.1007/s00253-012-4530-1. Epub 2012 Nov 16.
The cruciferous fungal pathogen Verticillium longisporum represents an allodiploid hybrid with long spores and almost double the amount of nuclear DNA compared to other Verticillium species. V. longisporum evolved at least three times by hybridization. In Europe, virulent A1xD1 and avirulent A1xD3 hybrids were isolated from the oilseed crop Brassica napus. Parental A1 or D1 species are yet unknown whereas the D3 lineage represents Verticillium dahliae. Eleven V. longisporum isolates from Europe or California corresponding to hybrids A1xD1 or A1xD3 were compared. A single characteristic type of nuclear ribosomal DNA could be assigned to each hybrid lineage. The two avirulent A1xD3 isolates carried exclusively D3 ribosomal DNA (rDNA) which corresponds to V. dahliae. The rDNA of all nine A1xD1 isolates is identical but distinct from D3 and presumably originates from A1. Both hybrid lineages carry two distinct isogene pairs of four conserved regulatory genes corresponding to either A1 or D1/D3. D1 and D3 paralogues differ in several single nucleotide polymorphisms. Southern hybridization patterns confirmed differences between the A1 and D1/D3 isogenes and resulted in similar patterns for D1 and D3. Distinct signatures of the Verticillium transcription activator (VTA)2 regulatory isogene pair allow identification of V. longisporum hybrids by a single polymerase chain reaction and the separation from haploid species as V. dahliae or Verticillium albo-atrum. The combination between VTA2 signature and rDNA type identification represents an attractive diagnostic tool to discriminate allodiploid from haploid Verticillia and to distinguish between A1xD1 and A1xD3 hybrids which differ in their virulence towards B. napus.
旋状镰刀菌病原菌长孢镰刀菌是一种异源二倍体杂种，与其他旋状镰刀菌物种相比，其孢子较长，核 DNA 含量几乎是其两倍。长孢镰刀菌通过杂交至少进化了三次。在欧洲，从油料作物油菜中分离出了毒力 A1xD1 和无毒 A1xD3 杂种。亲本 A1 或 D1 种仍不清楚，而 D3 谱系代表了大丽轮枝菌。对来自欧洲或加利福尼亚的 11 个长孢镰刀菌分离株，对应于 A1xD1 或 A1xD3 杂种进行了比较。可以为每个杂种谱系分配单一特征型核核糖体 DNA。两个无毒的 A1xD3 分离株仅携带 D3 核糖体 DNA（rDNA），与大丽轮枝菌相对应。所有九个 A1xD1 分离株的 rDNA 是相同的，但与 D3 不同，推测源自 A1。这两个杂种谱系都携带两对不同的四个保守调控基因的同工基因对，分别对应于 A1 或 D1/D3。D1 和 D3 旁系同源物在几个单核苷酸多态性中存在差异。Southern 杂交模式证实了 A1 和 D1/D3 同工基因之间的差异，并导致 D1 和 D3 产生相似的模式。Verticillium 转录激活因子（VTA）2 调控同工基因对的独特特征允许通过单个聚合酶链反应识别长孢镰刀菌杂种，并将其与作为大丽轮枝菌或旋状镰刀菌的单倍体物种分离。VTA2 特征和 rDNA 类型鉴定的组合代表了一种有吸引力的诊断工具，可以区分异源二倍体和单倍体旋状镰刀菌，并区分毒力不同的 A1xD1 和 A1xD3 杂种对油菜的影响。
