Department of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland.
INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France.
Environ Microbiol. 2023 Dec;25(12):3502-3511. doi: 10.1111/1462-2920.16490. Epub 2023 Sep 2.
Pseudomonas syringae is a bacterial complex that is widespread through a range of environments, typically associated with plants where it can be pathogenic, but also found in non-plant environments such as clouds, precipitation, and surface waters. Understanding its distribution within the environment, and the habitats it occupies, is important for examining its evolution and understanding behaviours. After a recent study found P. syringae living among a range of vascular plant species in Iceland, we questioned whether lichens could harbour P. syringae. Sixteen different species of lichens were sampled all over Iceland, but only one lichen genus, Peltigera, was found to consistently harbour P. syringae. Phylogenetic analyses of P. syringae from 10 sampling points where lichen, tracheophyte, and/or moss were simultaneously collected showed significant differences between sampling points, but not between different plants and lichens from the same point. Furthermore, while there were similarities in the P. syringae population in tracheophytes and Peltigera, the densities in Peltigera thalli were lower than in moss and tracheophyte samples. This discovery suggests P. syringae strains can localize and survive in organisms beyond higher plants, and thus reveals opportunities for studying their influence on P. syringae evolution.
丁香假单胞菌是一种广泛分布于多种环境中的细菌复合体，通常与植物相关，在植物中可能具有致病性，但也存在于非植物环境中，如云层、降水和地表水。了解其在环境中的分布以及它所占据的栖息地对于研究其进化和理解其行为非常重要。最近的一项研究发现，丁香假单胞菌存在于冰岛的多种维管植物物种中，于是我们开始质疑地衣是否能容纳丁香假单胞菌。我们在冰岛各地采集了 16 种不同的地衣，但只有一个地衣属，即 Peltigera，被发现始终容纳有丁香假单胞菌。对从 10 个同时采集地衣、木本植物和/或苔藓的采样点采集的丁香假单胞菌进行的系统发育分析表明，采样点之间存在显著差异，但不同植物和来自同一采样点的地衣之间没有差异。此外，虽然木本植物和 Peltigera 中的丁香假单胞菌种群存在相似性，但 Peltigera 叶状体中的密度低于苔藓和木本植物样本。这一发现表明，丁香假单胞菌菌株可以在高等植物以外的生物体内定位和生存，从而为研究它们对丁香假单胞菌进化的影响提供了机会。
