Gallup C A, Shew H D
Department of Plant Pathology, Campus Box 7903, North Carolina State University, Raleigh, NC 27695.
Plant Dis. 2010 May;94(5):557-562. doi: 10.1094/PDIS-94-5-0557.
Black shank, caused by the oomycete Phytophthora nicotianae, causes significant annual yield losses in tobacco. Race 3 of P. nicotianae is reported here for the first time from North Carolina. It was identified from a North Carolina tobacco field with a history of tobacco varieties with Phl gene resistance and numerous field sites with no known deployment of varieties with the Phl gene. Race 3 was originally described from cigar-wrapper tobacco in Connecticut in the 1970s, but has not been reported in any other location since. Race 3 was defined as overcoming the Phl gene from Nicotiana longiflora but not the Php gene from N. plumbaginifolia. Stem and root inoculations were conducted on a set of host differentials to determine the virulence of North Carolina isolates. Stem inoculation was unable to distinguish between races 0 and 3 of P. nicotianae and is not a reliable method of identifying these virulence types. Race 1 gave a unique phenotype using stem inoculation. Root inoculation was the only reliable means of distinguishing between races 0 and 3. This is the first report of race 3 in North Carolina and the first report of damage to seedlings from root inoculations and to plants containing the Phl gene in naturally infested soil.
由烟草疫霉这种卵菌引起的黑胫病，每年都会给烟草造成重大产量损失。烟草疫霉3号生理小种首次在北卡罗来纳州被发现。它是从北卡罗来纳州的一个烟草田鉴定出来的，该田种植过具有Phl基因抗性的烟草品种，还有许多未知是否种植过含Phl基因品种的田块。3号生理小种最初于20世纪70年代在康涅狄格州的雪茄外包叶烟草中被描述，但此后未在任何其他地方被报道过。3号生理小种被定义为能克服来自长花烟草的Phl基因，但不能克服来自蓝花烟草的Php基因。对一组鉴别寄主进行了茎部和根部接种，以确定北卡罗来纳州分离株的毒力。茎部接种无法区分烟草疫霉的0号和3号生理小种，不是鉴定这些毒力类型的可靠方法。1号生理小种在茎部接种时表现出独特的表型。根部接种是区分0号和3号生理小种的唯一可靠方法。这是北卡罗来纳州关于3号生理小种的首次报道，也是关于根部接种对幼苗以及对自然侵染土壤中含Phl基因植株造成损害的首次报道。
