Malapi-Wight Martha, Salgado-Salazar Catalina, Demers Jill E, Clement David L, Rane Karen K, Crouch Jo Anne
United States Department of Agriculture-Agriculture Research Service (USDA-ARS), Systematic Mycology and Microbiology Laboratory, Beltsville, MD 20705.
USDA-ARS, Systematic Mycology and Microbiology Laboratory; and Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ 08906.
Plant Dis. 2016 Jun;100(6):1093-1100. doi: 10.1094/PDIS-10-15-1159-RE. Epub 2016 Mar 22.
Early and accurate diagnosis of new plant pathogens is vital for the rapid implementation of effective mitigation strategies and appropriate regulatory responses. Most commonly, pathogen identification relies on morphology and DNA marker analysis. However, for new diseases, these approaches may not be sufficient for precise diagnosis. In this study, we used whole-genome sequencing (WGS) to identify the causal agent of a new disease affecting Sarcococca hookeriana (sarcococca). Blight symptoms were observed on sarcococca and adjacent Buxus sempervirens (boxwood) plants in Maryland during 2014. Symptoms on sarcococca were novel, and included twig dieback and dark lesions on leaves and stems. A Calonectria sp. was isolated from both hosts and used to fulfill Koch's postulates but morphology and marker sequence data precluded species-level identification. A 51.4-Mb WGS was generated for the two isolates and identified both as Calonectria pseudonaviculata. A single-nucleotide polymorphism at a noncoding site differentiated between the two host isolates. These results indicate that the same C. pseudonaviculata genotype has the ability to induce disease on both plant species. This study marks the first application of WGS for fungal plant pathogen diagnosis and demonstrates the power of this approach to rapidly identify causal agents of new diseases.
新植物病原体的早期准确诊断对于迅速实施有效的缓解策略和做出适当的监管反应至关重要。最常见的是，病原体鉴定依赖于形态学和DNA标记分析。然而，对于新出现的疾病，这些方法可能不足以进行精确诊断。在本研究中，我们使用全基因组测序（WGS）来鉴定一种影响胡氏清香桂（清香桂）的新疾病的病原体。2014年在马里兰州，清香桂和相邻的欧洲黄杨（黄杨木）植株上观察到了枯萎症状。清香桂上的症状是新出现的，包括嫩枝枯死以及叶片和茎上的深色病斑。从两个寄主上均分离出一种拟轮枝菌属真菌，并用于满足柯赫氏法则，但形态学和标记序列数据无法进行种水平鉴定。为这两个分离株生成了一个51.4 Mb的全基因组序列，并将两者均鉴定为伪舟形拟轮枝菌。两个寄主分离株在一个非编码位点的单核苷酸多态性存在差异。这些结果表明，相同的伪舟形拟轮枝菌基因型能够在这两种植物上引发疾病。本研究标志着全基因组测序首次应用于真菌植物病原体诊断，并证明了这种方法在快速鉴定新疾病病原体方面的强大作用。
