Wang Miao, Li Erqin, Liu Chen, Jousset Alexandre, Salles Joana F
Research Group of Microbial Community Ecology, Genomics Research in Ecology and Evolution in Nature, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands.
Plant-Microbe Interactions, Department of Biology, Utrecht University, Utrecht, Netherlands.
Front Microbiol. 2017 Oct 30;8:2102. doi: 10.3389/fmicb.2017.02102. eCollection 2017.
Plant-associated bacteria are known for their high functional trait diversity, from which many are likely to play a role in primary and secondary succession, facilitating plant establishment in suboptimal soils conditions. Here we used an undisturbed salt marsh chronosequence that represents over 100 years of soil development to assess how the functional traits of plant associated bacteria respond to soil type, plant species and plant compartment. We isolated and characterized 808 bacterial colonies from the rhizosphere soil and root endosphere of two salt marsh plants, and , along the chronosequence. From these, a set of 59 strains (with unique BOX-PCR patterns, 16S rRNA sequence and unique to one of the treatments) were further screened for their plant growth promoting traits (siderophore production, IAA production, exoprotease production and biofilm formation), traits associated with bacterial fitness (antibiotic and abiotic stress resistance - pH, osmotic and oxidative stress, and salinity) and metabolic potential. An overall view of functional diversity (multivariate analysis) indicated that the distributional pattern of bacterial functional traits was driven by soil type. Samples from the late succession (Stage 105 year) showed the most restricted distribution, harboring strains with relatively low functionalities, whereas the isolates from intermediate stage (35 year) showed a broad functional profiles. However, strains with high trait performance were largely from stage 65 year. Grouping the traits according to category revealed that the functionality of plant endophytes did not vary along the succession, thus being driven by plant rather than soil type. In opposition, the functionality of rhizosphere isolates responded strongly to variations in soil type as observed for antibiotic resistance ( = 0.014). Specifically, certain sp. and sp. strains revealed high resistance against abiotic stress and antibiotics and produce more siderophores, confirming the high plant-growth promoting activity of these two genera. Overall, this study contributes to a better understanding of the functional diversity and adaptation of the microbiome at typical salt marsh plant species across soil types. Specifically, soil type was influential only in the rhizosphere but not on the endosphere, indicating a strong plant-driven effect on the functionality of endophytes.
与植物相关的细菌以其高度的功能性状多样性而闻名，其中许多细菌可能在初级和次级演替中发挥作用，促进植物在次优土壤条件下的定植。在这里，我们使用了一个未受干扰的盐沼时间序列，该序列代表了超过100年的土壤发育过程，以评估与植物相关的细菌的功能性状如何响应土壤类型、植物物种和植物区室。我们沿着时间序列从两种盐沼植物的根际土壤和根内圈中分离并鉴定了808个细菌菌落。从这些菌落中，进一步筛选了一组59株菌株（具有独特的BOX-PCR模式、16S rRNA序列且对其中一种处理具有独特性），以检测它们的促进植物生长的性状（铁载体产生、吲哚-3-乙酸产生、胞外蛋白酶产生和生物膜形成）、与细菌适应性相关的性状（抗生素和非生物胁迫抗性——pH、渗透和氧化胁迫以及盐度）和代谢潜力。功能多样性的总体视图（多变量分析）表明，细菌功能性状的分布模式受土壤类型驱动。来自演替后期（第105年阶段）的样本显示出最受限的分布，含有功能相对较低的菌株，而来自中间阶段（第35年）的分离株显示出广泛的功能谱。然而，具有高性状表现的菌株大多来自第65年阶段。根据类别对性状进行分组显示，植物内生菌的功能在演替过程中没有变化，因此是由植物而非土壤类型驱动的。相反，如对抗生素抗性所观察到的（P = 0.014），根际分离株的功能对土壤类型的变化有强烈响应。具体而言，某些[具体植物1]属和[具体植物2]属菌株表现出对非生物胁迫和抗生素的高抗性，并产生更多的铁载体，证实了这两个属具有较高的促进植物生长活性。总体而言，本研究有助于更好地理解典型盐沼植物物种跨土壤类型的微生物组的功能多样性和适应性。具体而言，土壤类型仅在根际有影响，而对根内圈没有影响，这表明植物对内生菌的功能有很强的驱动作用。
