XVI International Botanical Congess

Tetraspores are liberated without a cell wall, within a sheath of hialine mucilage that attaches the spore to the substrate. A thin cell wall is produced soon after the attachment. The first indication of the germination process consists in a polarization of the spore's content, followed by the formation of a protuberance to where migrates most of the spore's protoplast. This process is probably driven by the production of a vacuole that enlarges as the protoplast is being pushed to the growing protrusion that will form a new cell. The apparent emptiness of the original spore, under a photonic microscope, in fact consists of a large vacuole surrounded by a thin envelope of cytoplasm, a few starch granules and a small nucleus. A clear pit-connection can be seen between the spore and the new elongated cell. Cytocalasin-B inhibits the formation of the protuberance, and therefore precludes germination.