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

Richter, F.; Calonne-Salmon, M.; van der Heijden, M. G. A.; Declerck, S.; Stanley, C. E.

doi:10.1101/2023.06.29.546436

Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.06.29.546436

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

Richter, F.·Calonne-Salmon, M.·van der Heijden, M. G. A.·Declerck, S.·Stanley, C. E.

View original source ↗Export metadata ↓

Abstract

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

Source connections

Published article ↗

Explore related subjects

microbiology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Richter, F., Calonne-Salmon, M., van der Heijden, M. G. A., Declerck, S., Stanley, C. E.. 2023-06-29. AMF-SporeChip provides new insights into arbuscular mycorrhizal fungal pre-symbiotic hyphal growth dynamics at the cellular level.. https://doi.org/10.1101/2023.06.29.546436

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Extreme temperature exposure has negative demographic consequences for Sulfolobus acidocaldarius

Microorganisms inhabiting geothermal springs and volcanic systems experience fluctuating temperatures that can periodically exceed their upper thermal limits, but the demographic consequences of such exposure remain poorly understood. Here, we investigated demographic responses of the thermophilic archaeon Sulfolobus acidocaldarius to an extreme temperature (94.1{degrees}C) under two regimes: sustained exposure varying in duration, and episodic exposure interspersed with recovery at a permissive temperature (75{degrees}C). Under sustained exposure, populations showed no detectable loss of viability after 15 min but declined thereafter, decreasing by approximately five orders of magnitude after 120 min. Under episodic exposure, populations remained viable across nine exposure-recovery cycles but declined in density with successive cycles. Similar responses were observed for three strains, including a DNA mismatch repair knockout ({Delta}nucS), indicating that mismatch repair deficiency did not affect viability or recovery. Together, these results demonstrate that S. acidocaldarius can withstand brief and repeated exposure to near-boiling temperatures, with mortality determined primarily by cumulative exposure duration rather than a fixed thermal threshold.

microbiology↗

bioRxiv2026

Bacteriophage and Antibiotic Resistance Are Positively Associated across a Phylogenetically Diverse Set of Clinical Pseudomonas aeruginosa Isolates

Co-administration of phages and antibiotics has been proposed as a therapeutic approach against antibiotic-resistant bacteria. The relationship, however, between antibiotic resistance and phage resistance in clinical isolates is unclear. Here, we examine associations between phage and antibiotic resistance profiles across a panel of Pseudomonas aeruginosa clinical isolates from the Centers for Disease Control (CDC) and Food and Drug Administration (FDA) Antimicrobial Resistance Isolate (ARI) Bank comprising 55 clinical strains with full genome sequences and antibiotic susceptibility testing (AST) data for 11 clinically relevant antibiotics. As phages in this study, we use three well-characterized, morphologically distinct phages, OMKO1, Luz19, and PAML31-1. We screen for phage resistance using a growth suppression assay, then conduct statistical analysis against antibiotic MIC (Minimum Inhibitory Concentration) data provided by the CDC to define association patterns across this dataset. We find multiple significant susceptibility correlations between pairs of antibiotics and phages, and a positive overall association between average phage resistance and antibiotic resistance across the 55 strains, even controlling for phylogenetic associations (=0.358, p<0.005). We conclude that phage and antibiotic resistance are positively associated across this clinical isolate collection, suggesting that the two resistance phenotypes are not independent in P. aeruginosa. These findings have implications for the development of phage-antibiotic cocktails.

microbiology↗

bioRxiv2026

The Estuary Effect: Variations in Temperature and Salinity Alter msh Promoter Activity in Vibrio cholerae

Vibrio cholerae, the facultative pathogen underlying cholera, naturally inhabits warm aquatic estuaries. Environmental persistence is enhanced by the ability of V. cholerae to colonize host reservoirs and form multicellular biofilms, causing seasonally endemic outbreaks in many tropical regions. Most toxigenic strains utilize the type IVa mannose-sensitive hemagglutinin (MSHA) pilus for host reservoir colonization and biofilm formation. Temperature and salinity can alter V. cholerae biofilm formation, yet their impact on MSHA production specifically remains largely unknown. Here, we utilized transcriptional reporters of predicted msh promoters (msh-P1/msh-P2/msh-P3) and functional assays, to determine temperature and salinity impacts on msh expression and pilus biogenesis. Under standard laboratory conditions (30{degrees}C, 1% NaCl) only msh-P1/P2 are active and inversely-coordinated with one another. Both msh-P1/P2 activity were elevated by high temperature (37{degrees}C) and low salinity (0.25%/0.5% NaCl), and reduced by low temperature (20{degrees}C/25{degrees}C) and high salinity (2%/3% NaCl). Temperature-mediated alterations in promoter activity were not immediately reflected in changes to cell-surface MSHA levels, whereas high salinity led to decreased MSHA production. Combining high temperature (37{degrees}C) and high salinity (2%/3% NaCl), attenuated the salinity-mediated reduction of msh-P1/P2 activity. Biofilm biomass levels were only substantially heightened at 25{degrees}C and 20{degrees}C, likely a result of no temperature-dependent changes in cell-surface MSHA, and additional temperature-controlled biofilm regulation previously described. We also found msh-P1/P2 promoter activity and MSHA production varies widely across toxigenic O1 and O139 serogroups despite complete sequence homology. These results shed new light on how key signals regulate MSHA pilus production to support V. cholerae persistence in aquatic environments.

microbiology↗