Soil-Driven Secrets: How Urban Soils Shape Extracellular Enzymatic Activities and Plant-Microbe Interactions

Anna Gillini ¹, Nataliya Bilyera ², Dalila Trupiano ¹, Iryna Loginova ², Michaela A. Dippold ², Gabriella Stefania Scippa ¹

Department of Biosciences and Territory, University of Molise, 86090 Pesche, Italy ¹, Geo-Biosphere Interactions, Department of Geosciences, University of Tübingen, Tübingen, Germany ²

The functioning of urban ecosystems and biodiversity, which are essential to human life and well-being, are under severe threat from anthropogenic pressure and climate change in recent years. According to recent research, biotic and abiotic soil components and plant roots interact underground influencing the biodiversity and ecosystems in a significant but hidden way. A controlled experiment was carried out using young Q. cerris seedlings and three distinct urban soils that were collected from three locations in the city of Campobasso (Molise region), following a specific gradient of vegetation fragmentation and urbanization, in order to provide insight into the function of these nearly unknown interactions in urban environments. Following physicochemical soil analyses, the amount of pollutants in the soil was used to develop a soil quality index (SQI) that linked site fragmentation to soil quality. These soils were then utilized in a rhizobox experiment to grow Q. cerris seedlings for two weeks. After the growth and settling phase, soil zymography was used to map the hotspot development and spatial distribution of the following enzymes: acid phosphatase (P-cycle), β-glucosidase (C-cycle), and leucine aminopeptidase (N-cycle). Analysis of the 2-D zymograms revealed that the soils varied spatially along the urbanisation or soil quality gradient, with the worst quality soils having the highest enzyme activity and hotspot values. Higher enzyme activity and, as a result, soil organic matter turnover were closely related to root activity intensity and could be linked to root exudation and/or rhizodeposition of substrates to modulate plant growth under unfavourable conditions by modifying soil components. Soils from rhizoboxes were collected to determine the composition of microbial communities and to predict their role in the soils. Analyses of bacterial communities using 16S rDNA gene sequencing suggested differences in the rhizosphere and bulk soils between the three sites studied. These findings revealed that soil quality or urbanization influenced not only the shift in extracellular enzyme activity, but also the changes in microbial communities.

Main author career stage: PhD student

Contribution type: Talk

First choice session: 2. Ecology

Second choice session: 3. Biodiversity and global change