Plant Conservation and Population Biology, KU Leuven, 3001 Leuven, Belgium.
Laboratory of Microbiology, Ghent University, 9000 Ghent, Belgium.
Syst Appl Microbiol. 2014 May;37(3):194-9. doi: 10.1016/j.syapm.2013.12.001. Epub 2014 Jan 14.
The best-known interaction between bacteria and plants is the Rhizobium-legume symbiosis, but other bacteria-plant interactions exist, such as between Burkholderia and Rubiaceae (coffee family). A number of bacterial endophytes in Rubiaceae are closely related to the soil bacterium Burkholderia caledonica. This intriguing observation is explored by investigating isolates from different geographic regions (Western Europe vs. sub-Saharan Africa) and from different niches (free-living bacteria in soil vs. endophytic bacteria in host plants). The multilocus sequence analysis shows five clades, of which clade 1 with two basal isolates deviates from the rest and is therefore not considered further. All other isolates belong to the species B. caledonica, but two genetically different groups are identified. Group A holds only European isolates and group B holds isolates from Africa, with the exception of one European isolate. Although the European and African isolates are considered one species, some degree of genetic differentiation is evident. Endophytic isolates of B. caledonica are found in certain members of African Rubiaceae, but only in group B. Within this group, the endophytes cannot be distinguished from the soil isolates, which indicates a possible exchange of bacteria between soil and host plant.
细菌和植物之间最著名的相互作用是根瘤菌-豆科植物共生，但也存在其他细菌-植物相互作用，如伯克霍尔德菌和茜草科（咖啡科）之间的相互作用。茜草科中的一些细菌内生菌与土壤细菌伯克霍尔德菌密切相关。通过研究来自不同地理区域（西欧与撒哈拉以南非洲）和不同生境（土壤中的自由生活细菌与宿主植物中的内生细菌）的分离物，探索了这一有趣的观察结果。多位点序列分析显示了五个分支，其中分支 1 有两个基础分离物与其他分支分离，因此不再进一步考虑。所有其他分离物都属于 B. caledonica 种，但鉴定出了两个具有遗传差异的组。组 A 仅包含欧洲分离物，组 B 包含来自非洲的分离物，但有一个欧洲分离物除外。尽管欧洲和非洲的分离物被认为是一个物种，但存在一定程度的遗传分化。在某些非洲茜草科植物中发现了 B. caledonica 的内生分离物，但仅存在于组 B 中。在这个组中，内生菌与土壤分离物无法区分，这表明细菌可能在土壤和宿主植物之间进行交换。
