Collecting and preserving mitotic spore mats

Camille Truong & Rosanne Healy, August 2022

Interested in collecting and identifying spore mats? Please reach out.

Remember that you need permits (or permission from private land owners) for collecting material.

What are spore mats

Some ectomycorrhizal Pezizomycete fungi (Ascomycota) can produce sexual meiospores in ascocarps (cup fungi or truffles) and asexual mitosopores (conidia) in spore mats. While the ascocarps are easily identified as species of cup fungi or truffles, spore mats are not generally recognizable as such. They appear a few days after rainfall as patches of mycelia with powdery spores on soil, fallen leaves, twigs or rocks. Some species are dense and fluffy, while others are thinner, and may follow the veins of dead leaves or twigs. Most begin white, but some species may turn a shade of red, pink, blue or yellow, and the mitotic spores may be one of these colors as well.

Teleomorph (truffle, above) and anamorph (yellowish spore mat, below) of Amylascus:

Teleomorph (truffle, below) and anamorph (whitish spore mat, above) of Ruhlandiella:

The role of mitotic spores for the life cycle of these fungi is not well understood, but they may act as spermatia to enhance the likelihood of finding compatible nuclei (outcrossing) in heterothallic species. Failure to colonize roots or germinate in culture indicate that the mitotic spores are likely not serving a propagative role.

Where to find spore mats

Spore mats can be spotted on bare soil or below thin litter, often at the border of trails, a few days after rain. If it’s too wet or raining they get flushed away; if it’s too dry they won’t grow. Some species, such as Plicaria endocarpoides and Geopyxis carbonaria are stimulated by fire.

Fruitbodies sometimes grow in close vicinity, so it is useful to look for truffles around.

Ruhlandiella spore mat at the border of a trail:

How to collect spore mats for the fungarium

Carefully remove the patch with a knife, including 1-2 cm of the subtending soil (helps keep it together) and place it in a small container.

Small Petri dishes work great, otherwise any plastic container or aluminium foil will do.
Record the date, location, canopy plants (putative mycorrhizal hosts) and basic habitat information.
While fresh, glue the patch on an archival paper card using diluted school glue and dry it overnight with a dehydrator set on low (below 50°) or in a closed plastic container with silica gel beads at the bottom.

If stored in a Petri dish, the collection can be dried directly by placing the Petri dish in the dehydrator or container with silica
Store collections in herbarium boxes (or Petri dishes sealed with their lid) horizontally to avoid crushing them.

Material needed for fungarium storage:

Specimen glued on heavy card stock paper:

Cover to preserve the specimen from being crushed:

How to sample material for DNA sequencing

Spore mats have few morphological characters and species identification relies mostly on microscopy and DNA. Microscopic characters can help to differentiate families (genera in some cases), but not species. Luckily they are easy to sequence.

To extract DNA from spore mats:

Sterilize a razor blade with a flame and/or an alcohol wipe, and carefully scrape the surface of the spore mat, avoiding any soil or debris from other organisms.
Put the powdery material in an Eppendorf tube with a DNA buffer (such as CTAB) and store at -20°C until DNA extraction.

It is easier to sample DNA from fresh material, but dried spore mats will work if stored properly (holding the soil and mycelium together so that dirt doesn’t mix with the hyphae).

Mycology protocols

Collecting and preserving mitotic spore mats

What are spore mats

Where to find spore mats

How to collect spore mats for the fungarium

How to sample material for DNA sequencing

Further reading