New insights into fungal-fungal interactions at the cellular level using a microfluidic device

Routinely, fungal-fungal interactions (FFIs) are studied on agar surfaces. However, this experimental format restricts high-resolution dynamic imaging. To gain experimental access to FFIs at the hyphal level in real-time, we developed a microfluidic platform, the FFI device, which utilises microchannel geometry to enhance the visibility of hyphal growth and provides control channels to allow comparisons between localised and systemic effects. We demonstrate its function by investigating the FFI between the biological control agent (BCA) Clonostachys rosea and the plant pathogen Fusarium graminearum. Microscope image analyses confirm the inhibitory effect of the necrotrophic BCA and we show for the first time that a loss of fluorescence in parasitised hyphae of GFP-tagged F. graminearum coincides with the detection of GFP in the mycelium of C. rosea. The versatility of our device to operate under both saturated and unsaturated conditions, coupled with its spatio-temporal output, opens new opportunities to study relationships between fungi.Routinely, fungal-fungal interactions (FFIs) are studied on agar surfaces. However, this experimental format restricts high-resolution dynamic imaging. To gain experimental access to FFIs at the hyphal level in real-time, we developed a microfluidic platform, the FFI device, which utilises microchannel geometry to enhance the visibility of hyphal growth and provides control channels to allow comparisons between localised and systemic effects. We demonstrate its function by investigating the FFI between the biological control agent (BCA) Clonostachys rosea and the plant pathogen Fusarium graminearum. Microscope image analyses confirm the inhibitory effect of the necrotrophic BCA and we show for the first time that a loss of fluorescence in parasitised hyphae of GFP-tagged F. graminearum coincides with the detection of GFP in the mycelium of C. rosea. The versatility of our device to operate under both saturated and unsaturated conditions, coupled with its spatio-temporal output, opens new opportunities to study relationships between fungi.