Hymenoscyphus fraxineus is a leaf pathogen of local Fraxinus species in the Russian Far East
Hymenoscyphus fraxineus is a leaf pathogen of local Fraxinus species in the Russian Far East
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DOI：
10.1111/ppa.12588
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发表时间：
2017-04-01
期刊：
影响因子：
2.7
通讯作者：
Hietala, A. M.
中科院分区：
文献类型：
--
作者：
Drenkhan, R.;Solheim, H.;Hietala, A. M.
欧洲火山灰的枯梢现象最早于1990年代初在欧洲发现。这种疾病是由入侵的子囊菌Hymenoscyphus fraxineus引起的，该子囊菌被认为起源于远东亚洲，在那里它被认为是一种无害的腐生性生物。本研究调查了H. fraxineus在俄罗斯远东地区的地方灰物种的组织，并评估其特定群体的遗传变异ITS测序。枝梢枯梢症状是H.欧洲白蜡树上的Fraxineus感染，在俄罗斯远东地区的水曲柳（Fraxinus mandshurica）和白蜡树（Fraxinus rhynchophylla）上很常见，但不多。高水平的病原体DNA与这些白蜡树种的坏死叶组织相关，表明当地的H。Fraxineus种群对它们的叶片具有致病性。但低水平的H.在有症状的枝条中检测到Fraxineus DNA，未能从这些组织中分离出这种真菌，以及在有症状的枝条中存在其他具有致病潜力的真菌，表明当地的H.秦皮属菌株可能不是该地区观察到的白蜡树梢枯梢症状的原因（或它们的作用可以忽略不计）。在ITS rDNA序列上，H.从俄罗斯远东和欧洲人群中分离的白蜡树属菌株表明，欧洲目前的白蜡树枯梢病流行可能不是直接起源于俄罗斯远东。对标本室资料的订正表明，最早的H. Fraxineus是1962年从俄罗斯远东地区采集的，是最古老的H. 2004年采集中国白蜡树标本。
Dieback of European ash was first observed in Europe in the early 1990s. The disease is caused by the invasive ascomycete Hymenoscyphus fraxineus, proposed to originate from Far East Asia, where it has been considered a harmless saprotroph. This study investigates the occurrence of H. fraxineus in tissues of local ash species in the Russian Far East, and assesses its population-specific genetic variation by ITS sequencing. Shoot dieback symptoms, characteristic of H. fraxineus infection on European ash, were common, but not abundant, on Fraxinus mandshurica and Fraxinus rhynchophylla trees in Far East Russia. High levels of pathogen DNA were associated with necrotic leaf tissues of these ash species, indicating that the local H. fraxineus population is pathogenic to their leaves. However, the low levels of H. fraxineus DNA detected in shoots with symptoms, the failure to isolate this fungus from such tissues, and the presence of other fungi with pathogenic potential in shoots with symptoms indicate that local H. fraxineus strains may not be responsible (or their role is negligible) for the observed ash shoot dieback symptoms in the region. Conspicuous differences in ITS rDNA sequences detected between H. fraxineus isolates from Russian Far East and European populations suggest that the current ash dieback epidemic in Europe might not directly originate from the Russian Far East. Revision of the herbarium material shows that the earliest specimen of H. fraxineus was collected in 1962 from the Russian Far East and the oldest H. fraxineus specimen of China was collected in 2004.