Microfungi associated with a myrmecophyte Macaranga bancana

Abstract

Microfungal populations associated with the domatia and food bodies of Macaranga bancana (Euphorbiaceae) and its obligate symbiotic ant Crematogaster borneensis were examined using culture-dependent methods. Forty-four fungal isolates were obtained and grouped into 15 operational taxonomic units (OTUs): 11 in Sordariomycetes and two each in Dothideomycetes and Eurotiomycetes. Hypocreales sp.3 (OTU3) was the commonest OTU isolated using the moist chamber method, followed by Paecilomyces sp. (OTU7), Chaetosphaeriaceae sp. (OTU10), Botryosphaeriaceae sp. (OTU12), and Aspergillus sp. (OTU15). Hypocreales sp.1 (OTU1) was the commonest OTU isolated by direct inoculation of the food bodies of M. bancana, darkened domatia materials, and ants and scale insects inside the domatia, followed by Hypocreales sp.3 (OTU3) and Chloridium sp. (OTU11). Molecular phylogenetic affi nities of the 15 OTUs suggested that the closest relatives of three, nine, and 13 OTUs were known as insect-associated fungi, plant pathogens, and saprobic fungi, respectively. The possible role of these fungi is discussed.

Fungi as mutualistic partners in ant-plant interactions

“…In the interaction between Crematogaster borneensis and Macaranga bancana , Hirose et al. (2013) found 15 OTUs, none of which were from the order Chaetothyriales.…”

“…These contrasting observations are likely the result of the use of different isolation methods to get fungal cultures: while Voglmayr et al. (2011) isolated the fungi directly from fungal “patches” of freshly opened domatia still inhabited by ant colonies, the method of Hirose et al. (2013) was rather unspecific, including a three week incubation step of the cut domatia before isolation of pure cultures from hyphae.…”

“…Some fungal strains isolated from galleries or domatia are ubiquitous and seem not to be specific to the ant species pointing towards an environmental acquisition ( Hirose et al., 2013 ; Nepel et al., 2014 ; Nepel et al., 2016 ; Vasse et al., 2017 ; Greenfield et al., 2021 ). Ant workers can bring spores or hyphal fragments from the environment into the nest by collecting pieces of soil and various organic debris from the ground or the canopy as has been highlighted in other interactions ( Abbott, 2002 ; Leroy et al., 2022 ).…”