Biology subjects

Meier, I. C.

Publications and source records attributed to Meier, I. C..

6 recordsLinked to original sources

bioRxiv2026

A transparent window into the rhizosphere: a simplified workflow for spatially resolved soil metabolomics

Root exudates play a central role in nutrient cycling, microbial recruitment, and plant-plant interactions, yet most experimental approaches for analyzing exudate chemistry rely on sterile hydroponic systems that poorly represent soil conditions. We present a low-cost, open-source, 3D-printed rhizobox platform and associated workflow that enable non-destructive root imaging and targeted rhizosphere soil sampling for LC-MS based metabolomics under realistic soil conditions. The design integrates a transparent removable window for repeated root observations, a defined soil volume to support spatially explicit sampling, and a blank-informed data-processing pipeline to distinguish plant-derived metabolites from soil and construction material background. We validated the system using the model plants Arabidopsis thaliana (Col-0) and Phragmites australis. We demonstrate reliable plant growth and consistent root development across the imaging window. We also show robust detection of species-specific rhizosphere metabolite profiles, with minimal variation in the vertical or temporal dimensions relative to the strong species effects. We further illustrate the application of the workflow in a factorial experiment manipulating social context (solo vs. conspecific pairs) and short-term heat stress in A. thaliana, showing that the approach is sensitive to treatment-associated changes in metabolite richness, diversity, and chemical composition in soil. The complete protocol, from rhizobox fabrication and assembly to soil extraction, LC-MS acquisition, and data curation can be implemented within 4-6 weeks using standard laboratory equipment and openly available design files. By combining ecological realism with analytical control, this workflow provides a broadly applicable method for quantifying rhizosphere metabolite dynamics across species, treatments, and spatial sampling zones, facilitating experimental studies of below-ground chemical processes in plant ecology.

plant biology↗

bioRxiv2026

How tree diversity and ectomycorrhizal dominance affect biomass allocation of mixed deciduous forests

Biomass and surface area allocation affect resource uptake and carbon (C) residence time in forests, but the influence of tree diversity on allocation remains poorly understood. Moreover, mycorrhizal associations can alter this relationship, which has been rarely tested in mature forests. We investigated the role of both the proportion of ectomycorrhizal (ECM) trees and tree diversity on tree biomass and surface area allocation across a dual gradient of tree diversity (0 - 1.68 Shannon diversity) and ECM dominance (0 - 100 %) in a mixed deciduous forest area in Central Germany. We found that the two gradients affected tree biomass and surface area differently and mostly independently. Tree diversity had no significant effect on biomass or surface area in the investigated forest area, but increased the spatial variability of the leaf area index (LAI) from 21 % to 40 %. In contrast, a higher proportion of ECM trees was associated with an increase in fruit biomass (from 10 to 141 g m-2) and LAI (from 4 to 7 m2 m-2). Although tree diversity and the portion of ECM produced similar parsimonious models for explaining belowground biomass and surface area, neither showed a significant direct effect. Notably, their interaction enhanced the spatial variability of fine root biomass and root surface area; that is, forests with high diversity and a greater proportion of ECM trees exhibited a more heterogeneous distribution of fine roots. Allocation to fine root biomass appeared independent of tree diversity and the proportion of ECM trees, being influenced primarily by stand structure, with higher allocations observed in stands with lower stem basal area. We conclude that biomass allocation in this Central European Forest, where resource availability is relatively uniform, is primarily productivity-driven. A comparison of the biotic influences shows that ECM trees have a stronger control on aboveground surface area and fruit biomass than tree diversity, which may contribute to the ability of dominant ECM trees, such as European beech, to outcompete light competitors, but also puts temperate ECM forests at risk of physiological failures in increasingly drier future conditions.

ecology↗

bioRxiv2024

Targeting the untargeted: Uncovering the chemical complexity of root exudates

The chemical complexity of root exudates has garnered significant attention in recent years, yet critical gaps remain in understanding the full scope of root exudate chemical variation across the plant kingdom. To address this, we conducted a systematic review of 57 studies, comprising 124 experiments, aimed at evaluating current methodologies and findings in untargeted root exudate chemical analysis. Our review revealed that hydroponic (44%) and soil-hydroponic hybrid (32%) sampling approaches, primarily utilising water as the collection medium, were the most common experimental setups. Liquid chromatography-mass spectrometry (LC-MS) was the predominant analytical technique used in 54% of the studies, followed by gas chromatography-mass spectrometry (GC-MS) in 31%. The average number of metabolites identified per analysis was 960, though the number of annotated metabolites varied considerably. Shikimates, phenylpropanoids, and carbohydrates were the most frequently identified classes, with their relative abundances varying widely. Several methodological challenges were highlighted, including inconsistencies in sampling techniques, underrepresentation of non-crop plants, and incomplete chemical annotation. To address these limitations, we propose a framework emphasising the need for representative exudate sampling, the use of multiple analytical approaches, the development of advanced bioinformatics tools, and the integration of these findings to enhance our understanding of root exudates and their ecological functions.

ecology↗

bioRxiv2023

A synthesis on the role of mycorrhizal fungal traits for understanding forest tree functions

O_LIAlmost all tree species are associated with mycorrhizal fungi, which help their hosts to acquire soil resources and influence the nutrient economy of the ecosystem. However, despite the fundamental nature of this symbiotic interaction, our understanding of the relationship between fungal properties and host functions is still in its infancy. C_LIO_LIWe compiled a unique database of fungal properties and examine the properties and traits of mycorrhizal fungi in relation to the three main functions of forest trees: resource acquisition, tree production, and carbon release (C). C_LIO_LIUsing quantitative synthesis and meta-analysis, we highlight the current strengths and knowledge gaps regarding tree species, spatial coverage and the relationships between fungal properties and tree functions. Most studies showed that the properties of fungal community assembly, host-symbiont interactions and soil exploration have a positive influence on the resource acquisition and production of host trees. According to a meta-analysis, the composition of the fungal community had a greater influence on resource uptake and tree production than taxon-specific effects. However, some properties of fungal community assembly were negatively related to root carbon (C) exudation (with low certainty), and the influence of these properties and soil exploration on carbon (C) release by host trees through root exudation and litter decomposition remained unclear. C_LIO_LIWe conclude that the influence of mycorrhiza on important tree functions remains an important area for future research, particularly with regard to fungal properties relating to soil exploration and tree properties relating to C release. Such research should progress beyond laboratory measurements of soft traits and increasingly focus on the mycorrhizal fungal properties that are most important for ecosystem functioning. C_LI

ecology↗

bioRxiv2020

Global Root Traits (GRooT) Database

MotivationTrait data are fundamental to quantitatively describe plant form and function. Although root traits capture key dimensions related to plant responses to changing environmental conditions and effects on ecosystem processes, they have rarely been included in large-scale comparative studies and global models. For instance, root traits remain absent from nearly all studies that define the global spectrum of plant form and function. Thus, to overcome conceptual and methodological roadblocks preventing a widespread integration of root trait data into large-scale analyses we created the Global Root Trait (GRooT) Database. GRooT provides ready-to-use data by combining the expertise of root ecologists with data mobilization and curation. Specifically, we (i) determined a set of core root traits relevant to the description of plant form and function based on an assessment by experts, (ii) maximized species coverage through data standardization within and among traits, and (iii) implemented data quality checks. Main types of variables containedGRooT contains 114,222 trait records on 38 continuous root traits. Spatial location and grainGlobal coverage with data from arid, continental, polar, temperate, and tropical biomes. Data on root traits derived from experimental studies and field studies. Time period and grainData recorded between 1911 and 2019 Major taxa and level of measurementGRooT includes root trait data for which taxonomic information is available. Trait records vary in their taxonomic resolution, with sub-species or varieties being the highest and genera the lowest taxonomic resolution available. It contains information for 184 sub-species or varieties, 6,214 species, 1,967 genera and 254 families. Due to variation in data sources, trait records in the database include both individual observations and mean values. Software formatGRooT includes two csv file. A GitHub repository contains the csv files and a script in R to query the database.

ecology↗

bioRxiv2020

The fungal collaboration gradient dominates the root economics space in plants

Plant economics run on carbon and nutrients instead of money. Leaf strategies aboveground span an economic spectrum from live fast and die young to slow and steady, but the economy defined by root strategies belowground remains unclear. Here we take a holistic view of the belowground economy, and show that root-mycorrhizal collaboration can short circuit a one-dimensional economic spectrum, providing an entire space of economic possibilities. Root trait data from 1,781 species across the globe confirm a classical fast-slow conservation gradient but show that most variation is explained by an orthogonal collaboration gradient, ranging from do-it-yourself resource uptake to outsourcing of resource uptake to mycorrhizal fungi. This broadened root economics space provides a solid foundation for predictive understanding of belowground responses to changing environmental conditions. One Sentence SummaryCollaboration broadens the root economics space ranging from do-it-yourself resource acquisition to outsourcing to mycorrhizal partners.

ecology↗