Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa.
Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa.
Microb Ecol. 2019 Jan;77(1):191-200. doi: 10.1007/s00248-018-1214-0. Epub 2018 Jun 9.
Plant-microbe interactions mediate both the invasiveness of introduced plant species and the impacts that they have in invaded ecosystems. Although the phylogenetic composition of the rhizospheric microbiome of Acacia dealbata (an invasive Australian tree species) has been investigated, little is known about the functional potential of the constituents of these altered microbial communities. We used shotgun DNA sequencing to better understand the link between bacterial community composition and functional capacity in the rhizospheric microbiomes associated with invasive A. dealbata populations in South Africa. Our analysis showed that several genes associated with plant growth-promoting (PGP) traits were significantly overrepresented in the rhizospheric metagenomes compared to neighbouring bulk soils collected away from A. dealbata stands. The majority of these genes are involved in the metabolism of nitrogen, carbohydrates and vitamins, and in various membrane transport systems. Overrepresented genes were linked to a limited number of bacterial taxa, mostly Bradyrhizobium species, the preferred N-fixing rhizobial symbiont of Australian acacias. Overall, these findings suggest that A. dealbata enriches rhizosphere soils with potentially beneficial microbial taxa, and that members of the genus Bradyrhizobium may play an integral role in mediating PGP processes that may influence the success of this invader when colonizing novel environments.
植物-微生物相互作用既能调节引入物种的入侵性，又能调节它们在入侵生态系统中的影响。虽然已经研究了金合欢（一种入侵的澳大利亚树种）根际微生物组的系统发育组成，但对于这些改变的微生物群落成分的功能潜力知之甚少。我们使用鸟枪法 DNA 测序来更好地了解与南非入侵金合欢种群相关的根际微生物组中细菌群落组成和功能能力之间的联系。我们的分析表明，与远离金合欢林的相邻块状土壤相比，根际微生物组的元基因组中与植物生长促进（PGP）特性相关的几个基因显著过表达。这些基因中的大多数参与氮、碳水化合物和维生素的代谢，以及各种膜转运系统。过表达的基因与少数细菌类群有关，主要是慢生根瘤菌属物种，这是澳大利亚金合欢的首选固氮根瘤菌共生体。总的来说，这些发现表明金合欢用潜在有益的微生物类群丰富了根际土壤，而慢生根瘤菌属的成员可能在介导 PGP 过程中发挥着重要作用，这些过程可能会影响这种入侵生物在新环境中的定植成功。
