Bacteria with Phosphate Solubilizing Capacity Alter Mycorrhizal Fungal Growth Both Inside and Outside the Root and in the Presence of Native Microbial Communities.

Yuli Marcela Ordoñez,Lidia Susana Lara,Belen Rocio Fernandez,Alia Rodriguez,Ian R Sanders,Daniel Uribe-Vélez,Ricardo Aroca

doi:10.1371/journal.pone.0154438

Yuli Marcela Ordoñez, Lidia Susana Lara + Show 5 more

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https://doi.org/10.1371/journal.pone.0154438

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Abstract

Arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing Pseudomonas bacteria (PSB) could potentially interact synergistically because PSB solubilize phosphate into a form that AMF can absorb and transport to the plant. However, very little is known about the interactions between these two groups of microorganisms and how they influence the growth of each other. We tested whether different strains of bacteria, that have the capacity to solubilize phosphate, are able to grow along AMF hyphae and differentially influence the growth of AMF both outside the roots of carrot in in vitro conditions and inside the roots of potato in the presence of a microbial community. We found strong effects of AMF on the growth of the different bacterial strains. Different bacterial strains also had very strong effects on the growth of AMF extraradical hyphae outside the roots of carrot and on colonization of potato roots by AMF. The differential effects on colonization occurred in the presence of a microbial community. Our results show that these two important groups of rhizosphere microorganisms indeed interact with each other. Such interactions could potentially lead to synergistic effects between the two groups but this could depend on whether the bacteria truly solubilize phosphate in the rhizosphere in the presence of microbial communities.

Highlights

Arbuscular mycorrhizal fungi (AMF) are present in most soils, forming associations with roots of approximately 80% of plant species [1]
The rhizosphere is regarded as a hotspot for microbial activity and recent studies indicate that this is the case for the mycorrhizosphere where soil bacteria may attach to extraradical AMF hyphae [2]
We conclude that P solubilizing-capable Pseudomonas bacteria and AMF can have positive effects on each others growth that could potentially lead to synergism between some combinations

Summary

Introduction

Arbuscular mycorrhizal fungi (AMF) are present in most soils, forming associations with roots of approximately 80% of plant species [1]. Mycorrhizal Fungi and P Solubilizing Bacteria roots, effectively increasing the soil volume from which minerals are acquired [1]. The rhizosphere is regarded as a hotspot for microbial activity and recent studies indicate that this is the case for the mycorrhizosphere where soil bacteria may attach to extraradical AMF hyphae [2]. The effect of arbuscular mycorrhizal fungal colonisation on the soil microbial community has been little studied. Among soil bacteria in the rhizosphere, those with the capacity to solubilize P are highly relevant when studying AMF interactions because these bacteria could potentially make available more soluble P for absorption by AMF hyphae

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