Gigaspora Margarita vs. Gigaspora Rosea

This image shows spores of both species photographed about 30 minutes after they were extracted and washed. At this time, each species is clearly delineated by a difference in color under reflected light from bifurcated fiber optic light pipes:

• Spores of Gi. rosea have a pink blush (examples designated by a red asterisk)

• Spores of Gi. margarita are bright white (examples designated by a cyan asterisk)

After 24 hours in a refrigerator, this difference disappears and then the only distinguishing feature is size. However, there is some overlap in the smallest spores (see cluster in lower left quadrant).

To set up a culture of BOTH species, there is only one option—spores clearly differentiating the two species must be picked immediately after extraction, incubated for at least 24 hours to remove any spores that may be degraded or parasitized, and then inoculate seedlings.

If nothing is done to the extracted mixture for 24 to 48 hours, then separation by size is the only remaining option. In this situation, only Gi. margarita will be separated definitively by picking the largest spores (outside the range of even the largest Gi. rosea spores). Picking the smallest spores could lead to a culture of either species. In this case, the only option is single-spore inoculation. That option is fine for research purposes, but deadly for a collection where the goal is to ensure the broadest genotypic background of any given strain.