The Lolium Pathotype of Magnaporthe oryzae Recovered from a Single Blasted Wheat Plant in the United States
The Lolium Pathotype of Magnaporthe oryzae Recovered from a Single Blasted Wheat Plant in the United States
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DOI：
10.1094/pdis-05-16-0700-re
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发表时间：
2017-05-01
期刊：
影响因子：
4.5
通讯作者：
Bavaresco, Jorge
中科院分区：
文献类型：
--
作者：
Farman, Mark;Peterson, Gary;Bavaresco, Jorge
小麦瘟病是一种毁灭性的疾病，首先在巴西发现，随后蔓延到南美洲的周边国家。2011年5月，在位于肯塔基州普林斯顿的肯塔基州大学小麦试验田中进行的疾病侦察鉴定出具有与周围小麦中存在的镰刀菌头枯病不同的疾病症状的单个植物。这种植物有一个患病的头，从轴的三分之一到顶端都被漂白成黄色。在健康组织的边界处观察到灰色菌丝体，对该材料进行显微镜检查显示梨形孢子与Magnaporthe sp.一致。随后通过分子标记的扩增和测序将病原体鉴定为Magnaporthe pigmentosa，基因组测序显示美国小麦稻瘟病分离株与M. 2002年从一年生黑麦草中分离到一个菌株，与引起南美小麦稻瘟病的M.生长室接种试验表明，该可疑分离物对小麦具有致病性。我们的结论是，这第一次发生在美国的小麦稻瘟病最有可能是由一个菌株，从地方性的百合属感染病原体，而不是从南美洲引进的异国情调。此外，我们还发现，能够感染小麦的M-16菌株在美国已经存在了至少16年。最后，证据表明，在普林斯顿的环境条件在2011年春季异常有利于早期生产的爆炸接种物。
Wheat blast is a devastating disease that was first identified in Brazil and has subsequently spread to surrounding countries in South America. In May 2011, disease scouting in a University of Kentucky wheat trial plot in Princeton, KY identified a single plant with disease symptoms that differed from the Fusarium head blight that was present in surrounding wheat. The plant in question bore a single diseased head that was bleached yellow from a point about one-third up the rachis to the tip. A gray mycelial mass was observed at the boundary of the healthy tissue and microscopic examination of this material revealed pyriform spores consistent with a Magnaporthe sp. The pathogen was subsequently identified as Magnaporthe oryzae through amplification and sequencing of molecular markers, and genome sequencing revealed that the U.S. wheat blast isolate was most closely related to an M. oryzae strain isolated from annual ryegrass in 2002 and quite distantly related to M oryzae strains causing wheat blast in South America. The suspect isolate was pathogenic to wheat, as indicated by growth chamber inoculation tests. We conclude that this first occurrence of wheat blast in the United States was most likely caused by a strain that evolved from an endemic Lolium-infecting pathogen and not by an exotic introduction from South America. Moreover, we show that M oryzae strains capable of infecting wheat have existed in the United States for at least 16 years. Finally, evidence is presented that the environmental conditions in Princeton during the spring of 2011 were unusually conducive to the early production of blast inoculum.