title: DESICCATION STRESS CAUSES STRUCTURAL AND ULTRASTRUCTURAL ALTERATIONS IN THE AEROTERRESTRIAL GREEN ALGA KLEBSORMIDIUM CRENULATUM (KLEBSORMIDIOPHYCEAE, STREPTOPHYTA) ISOLATED FROM AN ALPINE SOIL CRUST1.
abstract: Klebsormidium crenulatum (Kütz.) Lokhorst (Klebsormidiophyceae, Streptophyta) isolated from an alpine soil in Tyrol, Austria, was experimentally exposed to desiccation under various relative air humidities (RH 5, 75, and >95%, ambient air 55%-60%). The effects on the structure and ultrastructure of K. crenulatum after 1, 4, or 7 d of desiccation at 5, 75, and >95% RH were investigated. The cross walls were deformed to an undulated shape, and the cell diameter was reduced to ∼60% of the control. Regardless of the RH applied, in all cases the cytoplasm appeared denser compared to that of liquid-culture-grown cells. Electron-dense particles with diameters of 0.4 μm-0.8 μm were observed in the cytoplasm, likely representing lipid droplets. The chloroplasts of desiccated samples contained a large number of plastoglobules. The number and appearance of mitochondria were not visibly altered, as also verified by 3,3' dihexyloxacarbocyanine iodine (DIOC6) staining. The amphiphilic styryl dye FM 1-43 resulted in staining of the plasma membrane in cells from liquid culture. In 7 d desiccated samples, a marked fluorescence is seen in ∼40%-50% of the cells, which were dead. Actin microfilaments (MFs) were drastically disrupted after desiccation; only dotlike actin batches remained. These results demonstrate that flexibility of the cell walls and maintenance of the key organelles play a key role in the tolerance of desiccation stress in K. crenulatum.
authors.affiliation: University of Innsbruck, Institute of Botany, Department of Physiology and Cell Physiology of Alpine Plants, Sternwartestrasse 15, A-6020 Innsbruck, AustriaUniversity of Rostock, Institute of Biological Sciences, Applied Ecology, Albert-Einstein-Strasse 3, D-18057 Rostock, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Holzinger
authors.affiliation: University of Innsbruck, Institute of Botany, Department of Physiology and Cell Physiology of Alpine Plants, Sternwartestrasse 15, A-6020 Innsbruck, AustriaUniversity of Rostock, Institute of Biological Sciences, Applied Ecology, Albert-Einstein-Strasse 3, D-18057 Rostock, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Lütz
authors.affiliation: University of Innsbruck, Institute of Botany, Department of Physiology and Cell Physiology of Alpine Plants, Sternwartestrasse 15, A-6020 Innsbruck, AustriaUniversity of Rostock, Institute of Biological Sciences, Applied Ecology, Albert-Einstein-Strasse 3, D-18057 Rostock, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Karsten
keywords: DIOC6; FM 1-43; Streptophyta; actin microfilaments; cell wall; desiccation; green algae; ultrastructure