Long-Term Nutrient Enrichment of an Oligotroph-Dominated Wetland Increases Bacterial Diversity in Bulk Soils and Plant Rhizospheres
Long-Term Nutrient Enrichment of an Oligotroph-Dominated Wetland Increases Bacterial Diversity in Bulk Soils and Plant Rhizospheres
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DOI：
10.1128/msphere.00035-20
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发表时间：
2020-05-01
期刊：
影响因子：
4.8
通讯作者：
Peralta, Ariane L.
中科院分区：
文献类型：
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作者：
Bledsoe, Regina B.;Goodwillie, Carol;Peralta, Ariane L.
在营养有限的条件下，植物依靠根际微生物成员来促进养分的获取，作为回报，植物为这些与根相关的微生物提供碳源。然而，大气养分沉积可以通过改变土壤细菌组成和减少微生物类群与植物之间的合作来影响植物与微生物的关系。为了研究长期营养添加如何影响根际群落组成，我们比较了在营养贫乏的湿地生态系统中细菌(快速生长的共养生物、生长缓慢的寡养生物)和植物群落(C-3 Forb、C-4草)群落的相关特征。结果表明，贫养类群在土壤细菌群落中占主导地位，而施肥增加了土壤和根际群落中的寡营养类群的存在。此外，细菌物种多样性在施肥土壤中最大，特别是在散装土壤中。养分富集度(施肥量与未施肥量)和植物关联度(总体与根际)决定了细菌群落组成；与植物功能群(草与杂草)相关的细菌群落结构在处理内相似，但在不同施肥处理之间不同。核心禾本科微生物群由602个特有类群组成，核心草微生物群落由372个特有类群组成。Forb根际富含潜在的抗病细菌类群，草类根际富含与复杂碳分解相关的细菌类群。研究结果表明，施肥对土壤微生物群落具有很强的环境过滤作用，可以形成不同的根际群落，并能转移植物对根际微生物群落的影响。植物根际的这些分类变化可能会对植物的健康和与碳、氮循环相关的生态系统功能产生影响。合成化肥的使用以及化石燃料和生物质的燃烧增加了氮和磷的沉积，这导致了历史上营养含量低的生态系统的意外施肥。随着养分供应的增加，植物生物多样性预计将下降，而细菌群落中共养类群的丰度预计将增加。在这里，我们讨论了与不同植物功能类型(杂草、草)相关的细菌群落如何由于长期的营养丰富而发生变化。与其他研究不同，结果显示细菌多样性增加，特别是受精区的寡营养细菌。我们观察到，营养添加强烈地决定了草本植物根际的组成，这可能表明细菌群落中不同的代谢偏好。这项研究强调了以寡养菌为主的湿地的长期施肥如何以意想不到的方式改变根际细菌群落的多样性和新陈代谢。
In nutrient-limited conditions, plants rely on rhizosphere microbial members to facilitate nutrient acquisition, and in return, plants provide carbon resources to these root-associated microorganisms. However, atmospheric nutrient deposition can affect plant-microbe relationships by changing soil bacterial composition and by reducing cooperation between microbial taxa and plants. To examine how long-term nutrient addition shapes rhizosphere community composition, we compared traits associated with bacterial (fast-growing copiotrophs, slow-growing oligotrophs) and plant (C-3 forb, C-4 grass) communities residing in a nutrient-poor wetland ecosystem. Results revealed that oligotrophic taxa dominated soil bacterial communities and that fertilization increased the presence of oligotrophs in bulk and rhizosphere communities. Additionally, bacterial species diversity was greatest in fertilized soils, particularly in bulk soils. Nutrient enrichment (fertilized versus unfertilized) and plant association (bulk versus rhizosphere) determined bacterial community composition; bacterial community structure associated with plant functional group (grass versus forb) was similar within treatments but differed between fertilization treatments. The core forb microbiome consisted of 602 unique taxa, and the core grass microbiome consisted of 372 unique taxa. Forb rhizospheres were enriched in potentially disease-suppressive bacterial taxa, and grass rhizospheres were enriched in bacterial taxa associated with complex carbon decomposition. Results from this study demonstrate that fertilization serves as a strong environmental filter on the soil microbiome, which leads to distinct rhizosphere communities and can shift plant effects on the rhizosphere microbiome. These taxonomic shifts within plant rhizospheres could have implications for plant health and ecosystem functions associated with carbon and nitrogen cycling.IMPORTANCE Over the last century, humans have substantially altered nitrogen and phosphorus cycling. Use of synthetic fertilizer and burning of fossil fuels and biomass have increased nitrogen and phosphorus deposition, which results in unintended fertilization of historically low-nutrient ecosystems. With increased nutrient availability, plant biodiversity is expected to decline, and the abundance of copiotrophic taxa is anticipated to increase in bacterial communities. Here, we address how bacterial communities associated with different plant functional types (forb, grass) shift due to long-term nutrient enrichment. Unlike other studies, results revealed an increase in bacterial diversity, particularly of oligotrophic bacteria in fertilized plots. We observed that nutrient addition strongly determines forb and grass rhizosphere composition, which could indicate different metabolic preferences in the bacterial communities. This study highlights how long-term fertilization of oligotroph-dominated wetlands could alter diversity and metabolism of rhizosphere bacterial communities in unexpected ways.