03670nas a2200217   4500008004100000022001400041245009900055210006900154260001600223300001400239490000800253520293200261100002103193700002103214700001403235700001503249700001603264700001603280700002203296856013403318       2018                        eng d  a0191-291700aFirst Report of Phytophthora ramorum Lineage EU1 Infecting Douglas Fir and Grand Fir in Oregon0 aFirst Report of Phytophthora ramorum Lineage EU1 Infecting Dougl  cJan-02-2018  a455 - 4550 v1023 a<p>Sudden oak death (SOD) is caused by the introduced oomycete pathogen <em>Phytophthora ramorum</em> S. Werres, A. W. A. M. de Cock &amp; W. A. Man in’t Veld. This fungus-like organism has four clonal lineages: NA1, NA2, EU1, and EU2 (<a id="b3" class="ref bibr"></a>Grünwald et al. 2016; <a id="b4" class="ref bibr"></a>Prospero et al. 2007). Until recently, the NA1 lineage was the only clonal lineage of <em>P. ramorum</em> reported in wildland forests in the western United States. In contrast, EU1, NA1, and NA2 have all been found in U.S. nurseries (<a id="b2" class="ref bibr"></a>Grünwald et al. 2012). In the winter of 2015, a symptomatic <em>Notholithocarpus densiflorus</em> Manos, Cannon &amp; S.H.Oh (tanoak) was identified during a SOD helicopter survey in Curry County, OR. <em>P. ramorum</em> was isolated from symptomatic bark tissue. Subsequently, the isolate was determined to be of the EU1 lineage based on 14 microsatellite loci (<a id="b3" class="ref bibr"></a>Grünwald et al. 2016). Continued monitoring of the area in 2016 and 2017 has identified symptomatic <em>Abies grandis</em> (Douglas ex D. Don) Lindl. (grand fir; <em>n</em> = 3) and <em>Pseudotsuga menziesii</em> (Mirb.) Franco (Douglas fir; <em>n</em> = 2) saplings growing near infected tanoak trees in the mixed conifer forest of Curry County, OR. Symptoms with shoot blight for these species were similar to those described in the literature, including wilting and dieback of new shoots, brown discoloration of needles, and needle loss on young shoots. Isolations were made by plating surface-sterilized tip dieback tissue from <em>A. grandis</em> and <em>P. menziesii</em> on a Phytophthora-selective medium. Based on the presence of chlamydospores, characteristic hyphae, and sporangial morphology, the isolates were identified as <em>P. ramorum</em>. DNA was extracted from hyphae, and a portion of the <em>cellulose binding elicitor lectin (CBEL)</em> gene was amplified and sequenced using the CBEL5U and CBEL6L primers (<a id="b1" class="ref bibr"></a>Gagnon et al. 2014). The sequences of the unknown lineage were aligned to sequences of <em>CBEL</em> for NA1, NA2, EU1, and EU2 using the Staden package in GAP version 4.11.2. The lineage of the isolates from <em>A. grandis</em> and <em>P. menziesii</em> (GenBank accession nos. MF918374 and MF918375, respectively) had 100% identity to the EU1 reference sequences (GenBank nos. EU688952 and EF117945). To satisfy Koch’s postulates, three branches of <em>A. grandis</em> and <em>P. menziessii</em> were inoculated with the original EU1 isolates of <em>P. ramorum</em> from those hosts. Ten days after inoculation, the same pathogen was reisolated from symptomatic stem tissue of both tree species. The EU1 lineage is considered more aggressive than the NA1 lineage and is of opposite mating type to NA1, thus potentially resulting in establishment of sexual populations.</p>1 aLeBoldus, J., M.1 aSondreli, K., L.1 aSutton, W1 aReeser, P.1 aNavarro, S.1 aKanaskie, A1 aGrünwald, N., J.  uhttps://apsjournals.apsnet.org/doi/10.1094/PDIS-05-17-0681-PDNhttps://apsjournals.apsnet.org/doi/full/10.1094/PDIS-05-17-0681-PDN