Biology subjects

Calonne-Salmon, M.

Publications and source records attributed to Calonne-Salmon, M..

3 recordsLinked to original sources

bioRxiv2026

Intricate asymbiotic hyphal interactions of Rhizophagus irregularis revealed with single-plane observations in a new microfluidic device

Arbuscular mycorrhizal fungi (AMF) are essential symbionts to most land plants. There is great interest in using AMF inoculation treatments to enhance restoration or agricultural efforts. However, little is known about AMF asymbiotic interactions that could shape soil ecosystems and inoculation outcomes. Studying these early traits is challenging given the obligate nature of AMF. Microfluidic devices enable high-resolution, single-plane, time-resolved observation of AMF hyphal traits in controlled, plant-less environments. The AMF-AnastomosisChip, introduced in this work, additionally separates spores and hyphae into lanes for detailed observations prior to entering a shared interaction zone. Using this device with Rhizophagus irregularis, we phenotyped key hyphal traits from germination to anastomosis. We compared the effect of a fatty acid (FA) treatment to other environmental factors in shaping AMF growth and fusion (anastomosis). Among our results, we confirm known effects of the FA treatment in increasing hyphal branching and longevity but interestingly show that multiple hyphae in a lane can negate FA effects. We also newly reveal that anastomosis occurs for 100% of interactions among hyphae from different lanes, but only for 50% of in-lane interactions, potentially linked to spore origin. Our findings validate the AMF-AnastomosisChip as a versatile platform for increasing discovery in trait-based microbial ecology, including for asymbiotic AMF interactions with environmental factors. This work sets the foundation for future studies with the AMF-AnastomosisChip on the effects of nutrient content, plant-derived molecules, or microbial community members on the AMF traits characterized in this study.

microbiology↗

bioRxiv2023

Deciphering the biology and chemistry of the mutualistic partnership between Bacillus velezensis and the arbuscular mycorrhizal fungus Rhizophagus irregularis

Arbuscular mycorrhizal (AM) fungi (e.g. Rhizophagus irregularis) recruit specific bacterial species in their hyphosphere. However, the chemical interplay and the mutual benefit of this intricate partnership have not yet been investigated especially as it involves bacteria known as strong producers of antifungal compounds such as Bacillus velezensis. Here, we show that the soil dwelling B. velezensis migrates along the hyphal network of the AM fungus R. irregularis, forming biofilms and inducing metabolic fluxes that contributes to host plant root colonization by the bacterium. During hyphosphere colonization, R. irregularis modulates the biosynthesis of specific lipopeptides and antimicrobial compounds in B. velezensis as a mechanism toward-off mycoparasitic fungi and bacteria to ensure stable coexistence. These mutual benefits are extended into a tripartite context via the provision of enhanced protection to the host plant through the induction of systemic resistance.

microbiology↗

bioRxiv2023

AMF-SporeChip provides new insights into arbuscular mycorrhizal fungal pre-symbiotic hyphal growth dynamics at the cellular level.

O_LIArbuscular mycorrhizal fungi (AMF) form symbiotic associations with the majority of land plants and deliver a wide range of soil-based ecosystem services. Due to their conspicuous belowground lifestyle in a dark environment surrounded by soil particles, much is still to be learned about the influence of environmental (i.e., physical) cues on spore germination, hyphal morphogenesis and hyphopodium formation in AMF. C_LIO_LITo fill existing gaps in AMF knowledge, we developed a new microfluidic platform - termed the AMF-SporeChip - to immobilise Rhizophagus and Gigaspora spores and confront pre-symbiotic hyphae with physical obstacles. In combination with timelapse microscopy, the fungi could be examined at the cellular level and in real-time. C_LIO_LIThe AMF-SporeChip allowed us to acquire movies with unprecedented visual clarity and therefore identify various exploration strategies of AMF pre-symbiotic hyphae. We witnessed anastomosis formation involving directed hyphal growth in a "stop-and-go" manner, yielding visual evidence of pre-anastomosis signalling and decision-making. Remarkably, we also revealed a so-far undescribed reversible cytoplasmic retraction as part of a highly dynamic space navigation. C_LIO_LIOur findings demonstrated how AMF employ an intricate mechanism of space searching, involving reversible cytoplasmic retraction, branching and directional changes. In turn, the AMF-SporeChip is expected to open many future frontiers for AMF research. C_LI

microbiology↗