Plant Protection Division, Agroscope Changins-Wädenswil Research Station ACW, CH-8820, Wädenswil, Switzerland.
Environ Microbiol. 2014 Jul;16(7):2112-25. doi: 10.1111/1462-2920.12289. Epub 2013 Oct 17.
Erwinia amylovora causes a major disease of pome fruit trees worldwide, and is regulated as a quarantine organism in many countries. While some diversity of isolates has been observed, molecular epidemiology of this bacterium is hindered by a lack of simple molecular typing techniques with sufficiently high resolution. We report a molecular typing system of E. amylovora based on variable number of tandem repeats (VNTR) analysis. Repeats in the E. amylovora genome were identified with comparative genomic tools, and VNTR markers were developed and validated. A Multiple-Locus VNTR Analysis (MLVA) was applied to E. amylovora isolates from bacterial collections representing global and regional distribution of the pathogen. Based on six repeats, MLVA allowed the distinction of 227 haplotypes among a collection of 833 isolates of worldwide origin. Three geographically separated groups were recognized among global isolates using Bayesian clustering methods. Analysis of regional outbreaks confirmed presence of diverse haplotypes but also high representation of certain haplotypes during outbreaks. MLVA analysis is a practical method for epidemiological studies of E. amylovora, identifying previously unresolved population structure within outbreaks. Knowledge of such structure can increase our understanding on how plant diseases emerge and spread over a given geographical region.
火疫病菌引起了世界各地核果类果树的重大病害，在许多国家被视为检疫性生物。尽管已经观察到一些分离株的多样性，但由于缺乏足够高分辨率的简单分子分型技术，该细菌的分子流行病学受到阻碍。我们报告了一种基于可变数串联重复（VNTR）分析的火疫病菌分子分型系统。利用比较基因组工具鉴定了火疫病菌基因组中的重复序列，并开发和验证了 VNTR 标记。多基因座 VNTR 分析（MLVA）应用于代表病原体全球和区域分布的细菌收集物中的火疫病菌分离株。基于 6 个重复，MLVA 允许在来自全球起源的 833 个分离株的集合中区分 227 个单倍型。使用贝叶斯聚类方法在全球分离株中识别出三个地理上分离的群体。对区域性暴发的分析证实了存在多样化的单倍型，但在暴发期间也存在某些单倍型的高代表性。MLVA 分析是火疫病菌流行病学研究的一种实用方法，可以确定暴发期间未解决的种群结构。了解这种结构可以增加我们对特定地理区域植物病害如何出现和传播的理解。
