Fungus-Alga Ultrastructure in the Lichen, Cornicularia normoerica

Abstract

Ultrastructure in the symbiotic association in Cornicularia normoerica, fixed in glutaraldehyde, was demonstrated by staining either with potassium permanganate or osmium tetroxide‐thiocarbohydrazide‐osmium tetroxide (OTO) procedures modified for lichen tissues. Channels were observed to originate within the chloroplast, cross the algal cell wall and flare to open space shared with fungal and other algal cells. Tubules within the channels were extensions of chloroplast vesicles. Deeply staining channel walls, tubule elements, spherical bodies within the chloroplast, and organelles of the fungal cytoplasm suggested lipoid substances. The OTO procedure delineated zones in the thick cell walls of both symbionts. Their exterior boundaries were without discernible cellular membranes. The inner zone of the fungal cell wall was finely layered and particulate. No invasive fungal haustoria or zones of dissolution between fungus and alga were seen in any preparation.

SURVIVAL OF MYCORRHIZA FORMED BY CENOCOCCUM GEOPHILUM FR. IN DRY SOILS

“…The thick walls of the outer cells of mycorrhizas formed by C. geophilum closely resemble tbe gelatinous walls of many Ascomycotina of lichens and they have a similar microfibrillar fine structure (Bednar and Juniper, 1964;Walker, 1968). When wet, the walls swell and become gelatinous.…”

STRUCTURAL RESISTANCES TO MASS TRANSFER IN THE LICHEN XANTHORIA PARIETINA

“…Walker (1968) has suggested that the algae of Cornieularia aeuleata have channels running from the chloroplast, through the cell wall and into the intercellular space, but the features described could equally well be artefacts of specimen preparation. Vesicles in the sheath of Calothrix, the phycobiont of Liehina pygmaea, have been associated with crenulation in the algal cell wall and plasmalemma, and invaginations in the fungal plasmalemma, and proposed as transport structures (Peveling, 1973).…”

Physiological Aspects of Symbiotic Associations between Fungi and other Plants

“…The data are conflicting and too little are yet available for generalization. Walker (1968) could find no starch grains or plates associated with the pyrenoids of the phycobiont of Comicularia normoerica, which had the 'morphological properties of Trebouxia'. Similarly, Peat (1968) noted the absence of a-granules from the Nostoc phycobiont of Peltigera polydactyla.…”