Oedogonium Life Cycle

Oedogonium is a kind of green algae. As many as half of the various species of green algae reside in the United States. Oedogonium are distinguished by their interesting haploid life cycle.

This is because Oedogonium undergo both asexual and sexual reproduction. Oedogonium is a potentially useful organism worth further study for both educational and environmental purposes.

Oedogonium is a genus of green freshwater, filamentous macroalgae. The filaments of Oedogonium set it apart from other types of macroalgae, due to its rings of cells.

Several hundreds of species of Oedogonium are known to exist thus far. Typically they thrive in ponds, irrigation channels, wetlands or other shallow bodies of water. They use unbranched filaments to attach to a substrate, but they also float freely. Oedogonium is therefore considered to be a primitive form of algae.

Like many algae, Oedogonium exhibits a haploid life cycle. An alga starts as a diploid zygote, which undergoes meiosis and becomes haploid. Four cells developed from the zygote undergo mitosis and grows into the mature organism.

Oedogonium can grow via zoospores in asexual reproduction, or from the union of sperm and egg in sexual reproduction.

In Oedogonium asexual reproduction, the alga uses either zoospores or occasionally filament fragmentation and germination. The parent algae releases zoospores from the zoosporangium. The zoospore at first is enclosed in a vesicle.

It will then grow free of the vesicle and use flagella to move. Eventually the zoospore will lose its motile flagellum. Then it forms filaments by dividing over and over again.

In cell division of Oedogonium, new cell wall rings form at the apical end of the cell before mitosis. After mitosis, the split parental cell wall is connected with the ring. Subsequent cell division continually adds to these rings.

The new, cylindrical cells look stretched, since the newer daughter cell gets more ring cell wall material. The parental wall is not as stretched. This results in an apical cap. This chain of cells makes it filamentous. Inside each cell is a chloroplast, which hosts many pyrenoids or subcellular compartments. The rigid cell walls make a good substrate for other species.

Parent algae also possess antheridia and an oogonium, which produce sperm and egg, respectively. The oogonium appears swollen, with a large egg, whereas the antheridia resemble boxes. The motile sperm leave the antheridia and are chemically attracted to the oogonium. The sperm cell enters the oogonium through a pore.

When the two fuse and form a zygote, it results in the filamentous Oedogonium. Different species of Oedogonium possess different sizes of oogonia and antheridia. Some species do not have males that are reduced in size, and these are called macrandrous species. Short antheridia are considered a hallmark of nannandrous species or ones that have these smaller males.

The zygote is at first green but then undergoes changes in thickness to its cell wall, as well as potential color changes. After the zygote grows into the mature Oedogonium, cell division starts anew and builds upon the filament, starting the cycle again.

Species of Oedogonium have been proven to be good candidates for biomass applications. They are highly productive algae that tolerate a relatively wide range of temperatures and conditions.

Domesticated Oedogonium could be a great food source for the future. They could also serve as fertilizer.

These kinds of algae also provide good educational tools for students studying cell biology. Their unique life cycle demonstrates multiple types of reproduction and growth. While considered a relatively simple organism, learning about the development of these macroalgae has broad implications for its domestication and use.