Klebsormidium

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Klebsormidium
Klebsormidium bilatum

Klebsormidium bilatum

Systematics
without rank: Diaphoreticks
without rank: Archaeplastida
without rank: Chloroplastida
without rank: Charophyta
incertae sedis
Genre : Klebsormidium
Scientific name
Klebsormidium
PC Silva , Mattox & WH Blackwell

Klebsormidium is a species from the green algae group of Charophyta that occurs in freshwater. It includes around 17 species. Klebsormidium has been named Alga of the Year 2018 by the Phycology Section of the German Botanical Society (DBG). It can switch back and forth between apparently lifeless and reawakening, which means that it can also colonize places where no other plants can thrive.

features

The representatives form unbranched filaments from a row of cells that have a diameter of 4 to 23 micrometers. They either float freely or adhere to the substrate by means of a transparent, gelatinous and approximately circular foot at the end of the cell row. The cells are cylindrical, the cell wall is thin and smooth, in older cells it is occasionally clearly thickened and roughened.

The cells have a wall-mounted, band-shaped or belt-shaped and usually not strongly lobed chloroplast , which surrounds the cell interior in a ring shape but incompletely. The chloroplast has a single pyrenoid located in the center of the chloroplast , which is surrounded by a clearly recognizable starch coat.

The growth occurs through cell division in the thread. The asexual reproduction is performed by the disintegration of the threads or by forming a respective two geißeligen zoospore per cell. The zoospores are oval, have a flat belly side, the flagella start below the tip. The existence of sexual reproduction is controversial, it should be a question of isogamy : two equally large, two-flagellated sex cells fuse with one another.

In contrast to the more highly developed Charaphyceen, Klebsormidium has a special form of cytokinesis . Here the plasma membrane is constricted from the edges, similar to what is the case with animal cells. Even after the nucleus has been divided, there is a network of microtubules across the axis of division ( spindle apparatus ), which separates the daughter nuclei from one another. This is a feature that they share with the higher Charophyceae. However, no phragmoplast is formed, as is the case with higher Charophyceae and plants. In these, the separating plasma membrane within this spindle apparatus is formed by aggregating vesicles of the Golgi apparatus and not by constriction of the membrane.

Occurrence

The representatives of the genus occur on moist soils, on rocks that have been trickled over, as well as in standing and flowing waters. As pioneers, they colonized open surfaces with acidic to neutral soils, for example dunes, cooled lava or landslides in the forest and in the mountains. The genus is distributed both in the hot arid deserts of Africa and Australia and in the ice deserts of the Arctic. It spreads by wind, birds and other animals.

If they lack water, the Klebsormidium algae can solidify for several months in a state without any life reactions. As soon as the environment becomes moist again, they come back to life within a few minutes and begin photosynthesis .

Klebsormidium can also protect itself from UV radiation by synthesizing two so-called mycosporin-like amino acids (MAAs) as sun protection. These ring-shaped molecules inside the cell absorb harmful UV radiation and release this energy again in the form of heat and fluorescent lights. This protects the genetic material in the algae cells.

As a rapidly growing soil colonist, Klebsormidium is also interesting for applied research. The alga lives in biological soil crusts , which act as a base and fertilizer, and thus facilitate the colonization with plants in previously uninhabited locations. Soil crusts are already being used today to stop the expansion of deserts. They are also used by Australian cattle farmers to increase soil fertility and encourage the establishment of plants.

Systematics

Klebsormidium is a rather isolated genus within the Charophyta and was placed in an unsafe position near the base of this group by Lewis and McCourt .

The genus includes around 17 species worldwide. In Europe there are:

proof

  1. ↑ a b c d e f Klebsormidium : Commuter between seemingly dead and re-awakening is Alga of the Year 2018. Press release, Phycology Section of the German Botanical Society (DBG), from January 8, 2018.
  2. ^ Karl-Heinz Linne von Berg, Michael Melkonian a. a .: The Kosmos algae guide. The most important freshwater algae under the microscope. Kosmos, Stuttgart 2004, ISBN 3-440-09719-6 , p. 262.
  3. ↑ a b c Reference to the paragraph: Lokhorst, GM: Comparative taxonomic studies on the genus Klebsormidium (Charophyceae) in Europe. In: Cryptogamic Studies Volume 5, pp. 10-12, ISBN 3437308238 , 1996
  4. ↑ a b c Proof of the paragraph: Karl-Heinz Linne von Berg, Michael Melkonian u. a .: The Kosmos algae guide. The most important freshwater algae under the microscope. Kosmos, Stuttgart 2004, ISBN 3-440-09719-6 , p. 262.
  5. ^ PH Raven, FE Ray, SE Eichhorn: Biology of plants. 3rd edition de Gruyter 2000, p. 413.
  6. ^ Louise A. Lewis, Richard M. McCourt: Green Algae and the origin of land plants . In: American Journal of Botany . tape 91 , no. 10 , 2004, p. 1535–1556 ( abstract and full text ).

Web links

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