Spatiotemporal Dynamics of Maize (Zea mays L.) Root Growth and Its Potential Consequences for the Assembly of the Rhizosphere Microbiota

Abstract

Numerous studies have shown that plants selectively recruit microbes from the soil to establish a complex, yet stable and quite predictable microbial community on their roots – their “microbiome.” Microbiome assembly is considered as a key process in the self-organization of root systems. A fundamental question for understanding plant-microbe relationships is where a predictable microbiome is formed along the root axis and through which microbial dynamics the stable formation of a microbiome is challenged. Using maize as a model species for which numerous data on dynamic root traits are available, this mini-review aims to give an integrative overview on the dynamic nature of root growth and its consequences for microbiome assembly based on theoretical considerations from microbial community ecology.

Linking rhizosphere processes across scales: Opinion

“…It must be noted that the majority of soil microorganisms has limited access to available carbon and resides in a dormant state most of the time. In the immediate vicinity of the growing root tip however, the release of DOC via exudation transiently lifts the carbon limitation of microbial growth in soil and favours fast-growing copiotrophic taxa (Bonkowski et al, 2021;Rüger et al, 2021). Modelling these processes requires accounting explicitly for trade-offs associated with the release of enzymes by microorganism, a function currently assumed ubiquitous in the model, as well as the diffusion of released enzymes through the water phase from where they can reach and control hydrolysis of distant volumes, where it might initiate a priming effect on POM.…”

“…Direct imaging of microbes in the pore space is possible with unspecific stains or Card-FISH, combined with stable isotope labelling, but the procedures are so tedious that it will be long until large datasets will be available. In view of the dynamic changes of microbiota along roots as they grow (Bonkowski et al, 2021) it is an open question whether focussing on specific microbes (CARD-FISH) or rather unspecific approaches are more promising for a given purpose. Each approach is able to tackle different questions.…”

Survival of Plants During Short-Term BOA-OH Exposure: ROS Related Gene Expression and Detoxification Reactions Are Accompanied With Fast Membrane Lipid Repair in Root Tips

“…From these experiments, we conclude that not only the plants but also the microorganisms suffer from the allelochemicals and start defense and detoxification reactions. The root zone-dependent reaction of maize could be severely influenced by specific microbial assemblies, characteristic of the defined root zone (Bonkowski et al 2021 ). The density of microbial colonization and the species diversity within established microbiomes are described to be root zone dependent (Massalha et al 2017 ; Schmidt et al 2018 ; Rüger et al 2021 ).…”

Responses of Low-Cost Input Combinations on the Microbial Structure of the Maize Rhizosphere for Greenhouse Gas Mitigation and Plant Biomass Production

“…In this case, the activation of the inoculation effects in our experiment occurred before V15, and A. brasilense may have been replaced by other microorganisms. In addition, Bonkowski et al (2021) reported that the influence of plant growth stages is more significant than the fertilization level on the microbial community shift. Besides, the mature time of different roots and their rhizo deposits play an important role in microbiome assembly, which can cause the fluctuation in gene quantifications, as observed in our study.…”