A variety of melanised root-associated fungi from the Sydney basin form endophytic associations with Trifolium subterraneum

Knowledge of the abundance, diversity, and plant interactions of melanised root-associated fungi remains limited. The objective of this study was to isolate a wide variety of melanised root-associated fungi within the Sydney basin (NSW, Australia) and assess growth response of Trifolium subterraneum to inoculation with individual isolates. Of 902 root-associated fungi isolated from plant roots, 118 were melanised. All but two of these fungi were re-isolated from inoculated T. subterraneum seedlings after 7 weeks in a controlled environment. Approximately 60 % of the melanised root-associated fungi did not reduce plant growth. Twenty-four isolates tended to increase plant growth and were tentatively identified as predominantly ascomycetes, and one zygomycete. Melanised root-associated fungi appeared to form complex interactions with T. subterraneum, the natures of which remain to be further explored. Melanised root-associated fungi could potentially play key ecological roles including positively influencing edaphic conditions.

► 118 melanised root-associated fungi were isolated from within the Sydney basin.
► 116 colonised Trifolium subterraneum.
► Interactions ranged from mutualism to antagonism.
► 24 isolates increased the growth of Trifolium subterraneum over 7 weeks.
► Melanised root-associated fungi could potentially influence edaphic conditions.