: under construction
both ascospores
and mycosomes

Fungi have an unrecognized

type of spore that

may be hiding

in plain sight

 budding mycosomes
Endophytic fungi express a cryptic mycosome life history phase consisting of symbiotic vesicles and yeast-like or filamentous protoplasts that regenerate the walled phase. 

Mycosomes masquerade as vesicles, vacuoles and lipid bodies, hiding in plain sight in many cell types, including asci and ascospores. 

Mycosome intracellular protoplast life history explains fungal diversity within plants, and suggest a plant-based symbiotic transition from zoosporic to terrestrial fungi.

Cryptococcus stepposus yeast cells derived from  mycosomes (arrows) within an intact kiwifruit cell.

Hypomyces chrysospermus:

Mycosome protoplasts that developed from the fungal membrane enclosing a parasitized Psilotum nudum chloroplast

Mycosomes cultured from Cuscuta cell

extract, SYTO 9 stained for nucleic acids.

A brief introduction to

A Cuscuta pollen grain enveloped by tapetum-derived mycosomes. Right: Enlarging Ms, one of which has reverted to a budding Cladosporium conidium (arrow).

A budding Taphrina protoplast containing lipoid-organelles (red) and Staphylococcus warneri     

Mycosomes produced by Aureobasidium pullulans yeast cells cultured 5 days in 80% MsM, 20% Soy, transferred to MsM for 14 days. Mycosome nucleic acids fluoresce green with SYTO 9 stain.


A Rhodotorula cell forming lipoid-mycosomes (red)

Taphrina yeast cells developing from lipoid-mycosomes (red).



Egg yoke lipoid-Ms, 7 days in MsM, flooded

4 days over Sabouraud agar. Daughter-Ms fluoresce as punctate bodies.


cultured from egg yoke

Fungi identified from cultured egg yoke mycosomes: Aspergillus versicolor, Fusarium udum and F. nygamai  from cloned mycosome sequences. Mycosomes that reverted to walled cells included Chaetomium globosum, Cladosporium cladospoioides, Penicillium toxicarium, Rhodotorula glutinis (above) and Teratosphaeria sp. Unidentified fungi included two yeasts, one white, one haline glossy, and 8 filamentous fungi morphologically identified to genus: Penicillium (4), Cladosporium (2), Aspergillus (1), and Fusarium (1).

Mycosomes and Ms-protoplasts

do not stain for chitin cell walls

with Fungi Fluor, whereas adjacent developing Rhodotorula yeast cells fluoresce blue.


 Mycosome phase examples from fungi, plants and animals:

Mycosome examples from fungi, plants and animals