When to make partners in the city: phosphorous enrichment disrupt the
partnership between the invasive herb Ruellia nudiflora (Acanthaceae)
and arbuscular mycorrhizal fungi in a tropical urban environment.
The mutualistic relationship between plants and arbuscular mycorrhizal
fungi (AMF) is essential for optimal plant nutrition, enabling the plant
to better withstand biotic and abiotic stressors and enhancing its
chances of survival, reproduction, and colonization of new environments.
Urban soil nutrient enrichment may reduce the benefits of AMF for plant
nutrition, potentially reducing interaction with AMF in urban
environments. Here, we test this prediction by studying how urbanization
alter the plant-AMF interaction between the invasive herb Ruellia
nudiflora (Acanthaceae) and AMF in Mérida city. We collected soil and
plants from deep urban sites (DUS; e.g. sidewalks), open urban sites
(OUS; parks), and rural sites (RS) to analyze the soil nutrient content,
plant morphology, AMF-colonization rates, spore density, richness, and
diversity. Unexpectedly, DUS showed the lowest soil nutrient
concentrations except for phosphorus. Higher phosphorus levels in these
sites reduced AMF colonization, supporting the prediction of reduced
plant-AMF interactions in urban environments. We discovered that
potassium affects the plant-AMF association, an understudied effect.
Finally, urban plants produced smaller and more compact roots than rural
plants, and no differences on AMF communities were found between urban
and rural environments. To gain a better understanding of how AMF
contributes to plant colonization in urban environments, further studies