Morphology and ultrastructure ofInterfilumandKlebsormidium(Klebsormidiales, Streptophyta) with special reference to cell division and thallus formation.
Representatives of the closely related genera,InterfilumandKlebsormidium, are characterized by unicells, dyads or packets inInterfilumand contrasting uniseriate filaments inKlebsormidium. According to the literature, these distinct thallus forms originate by different types of cell division, sporulation (cytogony) versus vegetative cell division (cytotomy), but investigations of their morphology and ultrastructure show a high degree of similarity. Cell walls of both genera are characterized by triangular spaces between cell walls of neighbouring cells and the parental wall or central space among the walls of a cell packet, exfoliations and projections of the parental wall and cap-like and H-like fragments of the cell wall. In both genera, each cell has its individual cell wall and it also has part of the common parental wall or its remnants. Therefore, vegetative cells ofInterfilumandKlebsormidiumprobably divide by the same type of cell division (sporulation-like). Various strains representing different species of the two genera are characterized by differences in cell wall ultrastructure, particularly the level of preservation, rupture or gelatinization of the parental wall surrounding the daughter cells. The differing morphologies of representatives of various lineages result from features of the parental wall during cell separation and detachment. Cell division in three planes (usual inInterfilumand a rare event inKlebsormidium) takes place in spherical or short cylindrical cells, with the chloroplast positioned perpendicularly or obliquely to the filament (dyad) axis. The morphological differences are mainly a consequence of differing fates of the parental wall after cell division and detachment. The development of different morphologies within the two genera mostly depends on characters such as the shape of cells, texture of cell walls, mechanical interactions between cells and the influence of environmental conditions.
M.H. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Tereschenkivska St. 2, Kyiv UA-01001, Ukraine ; University of Rostock, Institute of Biological Sciences, Applied Ecology and Phycology, Albert-Einstein-Strasse 3, D-18059 Rostock, Germany.
Tatiana
T
Mikhailyuk
University of Innsbruck, Institute of Botany, Functional Plant Biology, Sternwartestrasse 15, A-6020 Innsbruck, Austria.
Andreas
A
Holzinger
Jan Kochanowski University, Institute of Biology, Dept of Botany, Świetokrzyska St. 15, PL-25-406, Kielce, Poland.
Andrzej
A
Massalski
University of Rostock, Institute of Biological Sciences, Applied Ecology and Phycology, Albert-Einstein-Strasse 3, D-18059 Rostock, Germany.
Ulf
U
Karsten
Interfilum; Klebsormidium; Streptophyta; molecular phylogeny; morphological characters; sporulation-like type of cell division; ultrastructure