Giant Spore Soil Fungus
Gigaspora margarita is an arbuscular mycorrhizal fungus whose spores are among the largest of any fungus, around a third of a millimeter across, large enough to see without a microscope.
Gigaspora margarita is an arbuscular mycorrhizal fungus whose spores are among the largest of any fungus, around a third of a millimeter across, large enough to see without a microscope. Like other members of its group, it lives in partnership with plant roots.
🧬 Field Guide Specimen: Open Giant Spore Soil Fungus in the CRV Science Field Guide to log the specimen, see its place among the Opisthokonta lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.
A Spore With Passengers: Bacteria Inside
Each spore harbors thousands of bacteria living inside the fungal cytoplasm, a bacterium called Candidatus Glomeribacter gigasporarum. The bacteria appear to influence the fungus's fitness and its energy metabolism, making this a nested symbiosis: a bacterium in a fungus in a plant.
Starting a Partnership
The spore germinates and produces hyphae that grow toward roots. Chemical signals from the plant, strigolactones, stimulate branching of the hyphae, and a fungal signal in turn prepares the root for colonization.
Asexual?
No sexual stage has ever been observed in these fungi, yet they seem to maintain genetic diversity. This puzzle, an old asexual lineage, remains a focus of research.
Giant Spore Soil Fungus at a Glance
| Property | Value |
|---|---|
| Scientific name | Gigaspora margarita |
| Kingdom | Fungi |
| Phylum | Glomeromycota |
| Class | Glomeromycetes |
| Order | Diversisporales |
| Family | Gigasporaceae |
| Field Guide group | Opisthokonta: Fungi (True Fungi & Lichens) |
| Diagnostic feature (Field Guide) | Enormous globose soil spores exceeding 300 micrometers, forming branched nutrient-exchange structures inside plant root cells and clusters of auxiliary cells in soil. |
| Group | Glomeromycota (Diversisporales) |
| Spore diameter | About 0.3 to 0.4 millimeters |