Ectomycorrhizal Fungal Communities Associated With Hopea odorata (Dipterocarpaceae) Planted in Tropical Urban Parks in Singapore

ABSTRACT

Members of the family Dipterocarpaceae are ecologically and economically important timber trees, many of which are threatened with extinction. Ectomycorrhizal (ECM) fungi form critical symbiotic associations with this family; however, their diversity and composition in tropical urban environments remain inadequately documented. Here, we characterize ECM fungal communities associated with the widely planted dipterocarp Hopea odorata in urban parks in Singapore through DNA metabarcoding. Fifty soil and root samples were collected beneath H. odorata at 10 locations, with two locations sampled within each of five parks. Based on the UNITE database, six ECM fungal genera and 21 ECM fungal operational taxonomic units (OTUs) were identified. Community composition varied significantly among parks, whereas alpha diversity remained consistent. Tomentella species were the most frequently encountered ECM fungal taxa and exhibited the greatest number of OTUs. None of the measured soil properties (pH, sand, silt, clay content) showed a significant relationship with alpha diversity or community composition. These findings indicate that H. odorata functions as a generalist host in urban parks, supporting low diversity ECM fungal assemblages but contributing to the conservation of ECM fungal diversity in tropical urban settings.