The genus Erwinia includes plant-associated pathogenic and non-pathogenic species. Among them, all species pathogenic to pome fruit trees (E. amylovora, E. pyrifoliae, E. piriflorinigrans, Erwinia sp. from Japan) cause similar symptoms, but differ in their degrees of aggressiveness, i.e. in symptoms, host range or both. The presence of plasmids of similar size, in the range of 30 kb, is a common characteristic that they possess. Besides, they share some genetic content with high homology in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes. Knowledge of the content of these plasmids and comparative genetic analyses may provide interesting new clues to understanding the origin and evolution of these pathogens and the level of symptoms they produce. Furthermore, genetic similarities observed among some of the plasmids (and genomes) from the above indicated pathogenic species and E. tasmaniensis or E. billingiae, which are epiphytic on the same hosts, may reveal associations that could expose the mechanisms of origin of pathogens. A summary of the current information on their plasmids and the relationships among them is presented here.

中文翻译：

---

对梨果树致病或附生相关的欧文氏菌属物种中质粒的功能和起源。


欧文氏菌属包括与植物相关的致病性和非致病性物种。其中，所有对仁果树致病的物种（来自日本的梨果桉、梨叶桉、梨花桉、欧文氏菌）都会引起类似的症状，但其侵袭性程度不同，即症状、寄主范围或两者兼而有之。存在大小相似（在 30 kb 范围内）的质粒是它们所具有的共同特征。此外，它们在与胞外多糖产生相关的几个基因以及一些其他基因中具有高度同源性的一些遗传内容，因此与毒力相关。了解这些质粒的内容和比较遗传分析可能会为了解这些病原体的起源和进化以及它们产生的症状水平提供有趣的新线索。此外，在来自上述致病物种和E. tasmaniensis或E. billingiae （附生在相同宿主上）的一些质粒（和基因组）之间观察到的遗传相似性可能揭示可能揭示病原体起源机制的关联。这里总结了有关它们的质粒及其之间关系的当前信息。