Non-Mycorrhizal Fungal Presence Within Roots Increases Across an Urban Gradient in Berlin, Germany

Abstract

Symbioses between plants and fungi are important in both promoting plant fitness and maintaining soil structure. The ways in which these relationships change across an urban gradient is subject to debate. Here we measured root colonisation including the presence of arbuscular mycorrhizal fungi, non-mycorrhizal fungi, and root hair presence. We found no evidence of changes in levels of arbuscular mycorrhizal fungal colonisation across an urban gradient, colonisation levels being driven instead by plant community. However, we did observe an increase in non-mycorrhizal fungal colonisation in association with increasing urbanity. Additionally, we observed an urban-related increase in root hair presence. Using principal component analysis we were able to provide strong evidence for these patterns being driven by an “urban syndrome”, rather than soil chemistry. Our findings have important implications for the wider understanding of abiotic stresses on fungal endophyte presence and shed light on the impacts of urbanity upon plant roots.

Soil microbial communities shift along an urban gradient in Berlin, Germany

“…One previous study, in the same system as this one, reported an increase in non-mycorrhizal colonization of plant roots in response to urbanity, whilst AMF colonization was not affected (Whitehead et al, 2022). Our observation of an increase in richness of the Ascomycota in response to urbanity, supports the hypothesis that these non-mycorrhizal endophytes were Ascomycota dark septate endophytes.…”

“…Previous research has suggested that globally, this phylum increases in abundance at urban locations (Delgado-Baquerizo et al, 2021). Whitehead et al (2022) found that AMF colonization rates in these sites 10.3389/fmicb.2022.972052 were likely driven by plant community composition, which was in turn driven by a syndrome of parameters very similar to the PCA axis 3 seen in this current study. Given the clear linearity seen in the NMDS plot between Glomeromycotan community, and PCA axis 3, we think it is likely that shifts in the Glomeromycotan community were driven by plant community composition.…”

“…The possibility of this is, however, subject to debate (Horn et al, 2017). Previous research, also from the study system used here, has demonstrated an increase in non-mycorrhizal root colonization in response to the urban syndrome, but a resilience of AMF colonization rates (Whitehead et al, 2022). It is as-yet unclear whether there is a similar resilience in Glomeromycotan community composition.…”