Mayerhofer Werner, Schintlmeister Arno, Dietrich Marlies, Gorka Stefan, Wiesenbauer Julia, Martin Victoria, Gabriel Raphael, Reipert Siegfried, Weidinger Marieluise, Clode Peta, Wagner Michael, Woebken Dagmar, Richter Andreas, Kaiser Christina
Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, A-1030, Austria.
Large-Instrument Facility for Environmental and Isotope Mass Spectrometry, University of Vienna, Vienna, A-1030, Austria.
New Phytol. 2021 Dec;232(6):2457-2474. doi: 10.1111/nph.17591. Epub 2021 Aug 6.
Ectomycorrhizal plants trade plant-assimilated carbon for soil nutrients with their fungal partners. The underlying mechanisms, however, are not fully understood. Here we investigate the exchange of carbon for nitrogen in the ectomycorrhizal symbiosis of Fagus sylvatica across different spatial scales from the root system to the cellular level. We provided N-labelled nitrogen to mycorrhizal hyphae associated with one half of the root system of young beech trees, while exposing plants to a CO atmosphere. We analysed the short-term distribution of C and N in the root system with isotope-ratio mass spectrometry, and at the cellular scale within a mycorrhizal root tip with nanoscale secondary ion mass spectrometry (NanoSIMS). At the root system scale, plants did not allocate more C to root parts that received more N. Nanoscale secondary ion mass spectrometry imaging, however, revealed a highly heterogenous, and spatially significantly correlated distribution of C and N at the cellular scale. Our results indicate that, on a coarse scale, plants do not allocate a larger proportion of photoassimilated C to root parts associated with N-delivering ectomycorrhizal fungi. Within the ectomycorrhizal tissue, however, recently plant-assimilated C and fungus-delivered N were spatially strongly coupled. Here, NanoSIMS visualisation provides an initial insight into the regulation of ectomycorrhizal C and N exchange at the microscale.
外生菌根植物与其真菌伙伴交换植物同化的碳以获取土壤养分。然而，其潜在机制尚未完全了解。在这里，我们研究了欧洲山毛榉外生菌根共生中从根系到细胞水平不同空间尺度上碳与氮的交换。我们向与年轻山毛榉树根系一半相关的菌根菌丝提供了氮标记的氮，同时使植物暴露于一氧化碳气氛中。我们用同位素比率质谱法分析了根系中碳和氮的短期分布，并在菌根根尖内的细胞尺度上用纳米二次离子质谱法（NanoSIMS）进行了分析。在根系尺度上，植物并没有将更多的碳分配到获得更多氮的根部分。然而，纳米二次离子质谱成像显示，在细胞尺度上，碳和氮的分布高度不均匀且在空间上显著相关。我们的结果表明，在宏观尺度上，植物不会将更大比例的光合同化碳分配到与提供氮的外生菌根真菌相关的根部分。然而，在外生菌根组织内，最近植物同化的碳和真菌提供的氮在空间上强烈耦合。在这里，NanoSIMS可视化提供了对外生菌根碳和氮交换在微观尺度上调控的初步见解。
