气候变化领域集成服务门户(CCPortal): Seagrass-mediated rhizosphere redox gradients are linked with ammonium accumulation driven by diazotrophs

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DOI	10.1128/spectrum.03335-23
	Seagrass-mediated rhizosphere redox gradients are linked with ammonium accumulation driven by diazotrophs
	Brodersen, Kasper Elgetti; Mosshammer, Maria; Bittner, Meriel J.; Hallstrom, Soren; Santner, Jakob; Riemann, Lasse; Kuhl, Michael
发表日期	2024
ISSN	2165-0497
起始页码	12
结束页码	4
卷号	12 期号:4
英文摘要	Seagrasses can enhance nutrient mobilization in their rhizosphere via complex interactions with sediment redox conditions and microbial populations. Yet, limited knowledge exists on how seagrass-derived rhizosphere dynamics affect nitrogen cycling. Using optode and gel-sampler-based chemical imaging, we show that radial O2 loss (ROL) from rhizomes and roots leads to the formation of redox gradients around below-ground tissues of seagrass (Zostera marina), which are co-localized with regions of high ammonium concentrations in the rhizosphere. Combining such chemical imaging with fine-scale sampling for microbial community and gene expression analyses indicated that multiple biogeochemical pathways and microbial players can lead to high ammonium concentration within the oxidized regions of the seagrass rhizosphere. Symbiotic N2-fixing bacteria (Bradyrhizobium) were particularly abundant and expressed the diazotroph functional marker gene nifH in Z. marina rhizosphere areas with high ammonium concentrations. Such an association between Z. marina and Bradyrhizobium can facilitate ammonium mobilization, the preferred nitrogen source for seagrasses, enhancing seagrass productivity within nitrogen-limited environments. ROL also caused strong gradients of sulfide at anoxic/oxic interfaces in rhizosphere areas, where we found enhanced nifH transcription by sulfate-reducing bacteria. Furthermore, we found a high abundance of methylotrophic and sulfide-oxidizing bacteria in rhizosphere areas, where O2 was released from seagrass rhizomes and roots. These bacteria could play a beneficial role for the plants in terms of their methane and sulfide oxidation, as well as their formation of growth factors and phytohormones. ROL from below-ground tissues of seagrass, thus, seems crucial for ammonium production in the rhizosphere via stimulation of multiple diazotrophic associations.IMPORTANCESeagrasses are important marine habitats providing several ecosystem services in coastal waters worldwide, such as enhancing marine biodiversity and mitigating climate change through efficient carbon sequestration. Notably, the fitness of seagrasses is affected by plant-microbe interactions. However, these microscale interactions are challenging to study and large knowledge gaps prevail. Our study shows that redox microgradients in the rhizosphere of seagrass select for a unique microbial community that can enhance the ammonium availability for seagrass. We provide first experimental evidence that Rhizobia, including the symbiotic N2-fixing bacteria Bradyrhizobium, can contribute to the bacterial ammonium production in the seagrass rhizosphere. The release of O2 from rhizomes and roots also caused gradients of sulfide in rhizosphere areas with enhanced nifH transcription by sulfate-reducing bacteria. O2 release from seagrass root systems thus seems crucial for ammonium production in the rhizosphere via stimulation of multiple diazotrophic associations. Seagrasses are important marine habitats providing several ecosystem services in coastal waters worldwide, such as enhancing marine biodiversity and mitigating climate change through efficient carbon sequestration. Notably, the fitness of seagrasses is affected by plant-microbe interactions. However, these microscale interactions are challenging to study and large knowledge gaps prevail. Our study shows that redox microgradients in the rhizosphere of seagrass select for a unique microbial community that can enhance the ammonium availability for seagrass. We provide first experimental evidence that Rhizobia, including the symbiotic N2-fixing bacteria Bradyrhizobium, can contribute to the bacterial ammonium production in the seagrass rhizosphere. The release of O2 from rhizomes and roots also caused gradients of sulfide in rhizosphere areas with enhanced nifH transcription by sulfate-reducing bacteria. O2 release from seagrass root systems thus seems crucial for ammonium production in the rhizosphere via stimulation of multiple diazotrophic associations.
英文关键词	ammonium; diazotrophs; redox conditions; rhizosphere; seagrass
语种	英语
WOS研究方向	Microbiology
WOS类目	Microbiology
WOS记录号	WOS:001176102900001
来源期刊	MICROBIOLOGY SPECTRUM
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/296343
作者单位	University of Copenhagen; BOKU University
推荐引用方式 GB/T 7714	Brodersen, Kasper Elgetti,Mosshammer, Maria,Bittner, Meriel J.,et al. Seagrass-mediated rhizosphere redox gradients are linked with ammonium accumulation driven by diazotrophs[J],2024,12(4).
APA	Brodersen, Kasper Elgetti.,Mosshammer, Maria.,Bittner, Meriel J..,Hallstrom, Soren.,Santner, Jakob.,...&Kuhl, Michael.(2024).Seagrass-mediated rhizosphere redox gradients are linked with ammonium accumulation driven by diazotrophs.MICROBIOLOGY SPECTRUM,12(4).
MLA	Brodersen, Kasper Elgetti,et al."Seagrass-mediated rhizosphere redox gradients are linked with ammonium accumulation driven by diazotrophs".MICROBIOLOGY SPECTRUM 12.4(2024).