Dr. Dennis Walker,   Department of Biological Sciences,   Humboldt State University

 

Psilotum Gametophyte Ultrastructure

Walker, D.K. and R.W. Davis. 1972. The Hyphal Plexus of Psilotum nudum gametophytes
      Proc. EMSA 30th Ann. Mtg. Pages 233-233

      A study of the gametophyte stage of the Psilotum nudum life cycle. "Whiskfern"gametophytes were collected at Humboldt State University from root-bound pots in the greenhouse, and the specimens were prepared and examined in the transmission electron microscope laboratory of the Department of Biological Sciences. Cells in the center of this heterotrophic thallus are invaded by an endophytic fungus. The gametophyte consumes digestible constituents of the fungal hyphae as a food source, leaving the indigestible parts in a knot-like lump, the "hyphal plexus", in the center of the cell. Surplus carbohydrates are stored as starch in amyloplasts,

Psilotum nudum gametophyte showing the apical meristems (AM), dichotomous branching (DB), antheridia (A), and the point of spore germination (SG) photomicrograph of Psilotum nudum gametophyte anatomy showing a gametophyte nucleus (PN), endophytic fungal hyphae (H), fungal vesicles (V), and examples of the hyphal plexus (HP) photomicrograph of Psilotum nudum gametophyte tissue showing gametophyte nuclei (PN), hyphae (H), vesicles (V), and hyphal plexus (HP) development stages photomicrograph of Psilotum nudum gametophyte cell showing cell wall (CW), nucleus (PN), and cytoplasm (PC), of the gametophyte cell; and hyphae (H), vesicles (V), and hyphal plexus (HP) of the endophytic fungus
       
electron micrograph of Psilotum nudum amyloplast in gametophyte showing plastid envelope (arrows), and starch grains (S) electron micrograph of Psilotum nudum gametophyte cell showing its cell wall (W), cytoplasm (PC), and the endophytic fungal hyphae (H) electron micrograph showing the nucleus (N), nuclear envelope (NE), cytoplasm (HC), and cell wall (HW) of an endophytic fungal hypha within the cytoplasm (PC) of a Psilotum nudum gametophyte cell electron micrograph of Psilotum nudum gametophyte cell showing its nucleus (PN), cytoplasm (PC), and the endophytic fungal hyphae (H)
       
electron micrograph of the endophytic fungal hyphae (H), and a developing hyphal plexus (HP) within the cytoplasm (PC) of a Psilotum nudum gametophyte cell electron micrograph of Psilotum nudum gametophyte cell showing its cytoplasm (PC), and cell wall (W), and the hyphae (H), and fully-developed hyphal plexus (HP) of the endophytic fungus electron micrograph of developing (YP), and fully-developed (OP) hyphal plexuses surrounded by the cytoplasm (PC) of a Psilotum nudum gametophyte cell electron micrograph of Psilotum nudum gametophyte cell showing its cytoplasm (PC), and cell wall (W) surrounding a fully-developed hyphal plexus (HP)