Department of Botany and Plant Pathology, 2082 Cordley Hall, Oregon State University, Corvallis, OR 97331.
Department of Crop and Soil Science, 3017 Agriculture and Life Sciences Building, Oregon State University, Corvallis, OR 97331.
Plant Dis. 2020 May;104(5):1500-1506. doi: 10.1094/PDIS-04-19-0808-RE. Epub 2020 Feb 26.
Widespread symptoms of root rot and mortality on and were observed in two horticultural nurseries in Oregon, leading to the isolation of a sp. from diseased roots. Based on morphology and sequencing the internal transcribed spacer ITS1-5.8S-ITS2 region, isolates were identified as the invasive pathogen , causal agent of Port-Orford-cedar (POC; ) root disease. Additional sequencing of the cytochrome c oxidase subunit 1 and 2 genes identified all isolates as belonging to the PNW lineage. Utilizing recovered isolates plus a POC-wildlands isolate and susceptible POC as controls, we completed Koch's postulates on potted and plants. Nursery isolates were more aggressive than the forest isolate, which was used in the POC resistance breeding program. Increased aggressiveness was confirmed using a branch stem dip assay with four POC clones that differed in resistance, although no isolate completely overcame major-gene resistance. Isolates were sensitive to mefenoxam, a fungicide commonly used to suppress spp. growth in commercial nurseries. Although POC resistance is durable against these more aggressive nursery isolates, the expanded host range of challenges POC conservation through the continued movement of by the nursery industry.
在俄勒冈州的两个园艺苗圃中，观察到 和 出现了广泛的根腐病症状和死亡率，导致从患病根部分离出 种。基于形态学和测序内部转录间隔区 ITS1-5.8S-ITS2 区域，分离物被鉴定为入侵病原体 ，是港口奥福德雪松（POC；）根病的病原体。细胞色素 c 氧化酶亚基 1 和 2 基因的进一步测序将所有分离物鉴定为 PNW 谱系。利用回收的分离物加上 POC 野生种群分离物和易感 POC 作为对照，我们完成了盆栽 和 植物上的柯赫假设。苗圃分离物比用于 POC 抗性育种计划的森林分离物更具侵略性。使用具有不同抗性的四个 POC 克隆进行的分支茎浸蘸试验证实了这种增加的侵略性，尽管没有分离物完全克服了主要基因抗性。分离物对甲霜灵敏感，甲霜灵是一种常用于抑制商业苗圃中 种生长的杀菌剂。尽管 POC 对这些更具侵略性的苗圃分离物具有持久的抗性，但 通过苗圃行业的持续迁移， 的扩大宿主范围对 POC 的保护构成了挑战。
