Characterisation of microbial communities colonising the hyphal surfaces of arbuscular mycorrhizal fungi

Abstract

Arbuscular mycorrhizal fungi (AMF) are symbiotic soil fungi that are intimately associated with the roots of the majority of land plants. They colonise the interior of the roots and the hyphae extend into the soil. It is well known that bacterial colonisation of the rhizosphere can be crucial for many pathogenic as well as symbiotic plant-microbe interactions. However, although bacteria colonising the extraradical AMF hyphae (the hyphosphere) might be equally important for AMF symbiosis, little is known regarding which bacterial species would colonise AMF hyphae. In this study, we investigated which bacterial communities might be associated with AMF hyphae. As bacterialhyphal attachment is extremely difficult to study in situ, we designed a system to grow AMF hyphae of Glomus intraradices and Glomus proliferum and studied which bacteria separated from an agricultural soil specifically attach to the hyphae. Characterisation of attached and non-attached bacterial communities was performed using terminal restriction fragment length polymorphism and clone library sequencing of 16S ribosomal RNA (rRNA) gene fragments. For all experiments, the composition of hyphal attached bacterial communities was different from the non-attached communities, and was also different from bacterial communities that had attached to glass wool (a non-living substratum). Analysis of amplified 16S rRNA genes indicated that in particular bacteria from the family of Oxalobacteraceae were highly abundant on AMF hyphae, suggesting that they may have developed specific interactions with the fungi.

Linking 3D Soil Structure and Plant-Microbe-Soil Carbon Transfer in the Rhizosphere

“…We assume that the highly enriched spot represents bacterial cells bound to the fungal hypha. Such strong association of bacterial cells to the hyphal surface was shown before (Artursson et al, 2006;Scheublin et al, 2010;Worrich et al, 2017). As the turnover rate of bacteria is generally considered to be higher compared to fungi (Rousk and Bååth, 2011), the bacteria or group of bacteria might have been transferred to the fungal hypha.…”

Symbiotic relationships between soil fungi and plants reduce N2O emissions from soil

“…Several studies also show that AMF influence bacterial communities inhabiting the rhizosphere and mycorrhizosphere (Ames et al, 1984;Scheublin et al, 2010), including shifts in denitrifying communities (Amora-Lazcano et al, 1998;Veresoglou et al, 2012b). AMF influence the N cycle and can take up significant amounts of nitrogen (Hodge and Fitter, 2010;Veresoglou et al, 2012a).…”

Autoregulation of Nodulation Interferes with Impacts of Nitrogen Fertilization Levels on the Leaf-Associated Bacterial Community in Soybeans

“…Recently, it was shown that the bacterial and fungal community structures in the roots of symbiosis-defective mutants of Medicago truncatula (32) and soybean (22) differ from those in the roots of wild-type host plants; it was also shown that certain microbes preferentially associate with arbuscular mycorrhizal roots (41) and nodulated (Nod ϩ ) roots (22). However, unexpectedly, analyses of the rhizosphere community in soybeans have revealed that the bacterial community in nonnodulated soybeans is more similar to that in hypernodulated soybeans than to that in wild-type soybeans (22).…”