Pyropia gardneri
| Pyropia gardneri | ||||||||||||
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| Scientific name | ||||||||||||
| Pyropia gardneri | ||||||||||||
| ( GMSmith & Hollenberg ) SC Lindstrom |
Pyropia gardneri is a red marine alga of the order Bangiales . Like all species of the genus Pyropia, it livesinthe intertidal zone and shows the two-part heterophasic generation change characteristic of the Bangiales, with the haploid generationgrowing epiphytically on brown algae of the order Laminariales , while the microscopic diploid generation is mostly hidden in the empty shells of marine animals.
Life cycle
The life cycle of P. gardneri was studied on the Pacific coast in British Columbia ( Canada ). There the first haploid plants ( thalli ) appear on young phylloids of their host at the end of February . Like these, they are leaf-like, but only one cell layer thick and anchored in the host with rhizoids . Asexual reproduction begins immediately , as individual cells at the edge of the phylloid detach as monospores. When these touch a host phylloid, they germinate by sending long rhizoids into the spaces between the cells and then forming their own phylloid. This is how P. gardneri spreads until sexual reproduction begins in late April . The red algae as with all unbegeißelten male gametes , the spermatia occur at 64 in a Spermatiummutterzelle by these shares many cases. Then they are released and passively spread by the water current. The female gametes, called carpogonia, are single cells of the single-layer phylloid that develop a small swelling, the prototrichogyne, on both sides of the phylloid, through which fertilization can take place. This happens when a spermatium attaches itself to a prototrichogyne and its cell nucleus migrates through this into the carpogon.
The fertilized carpogonium, the zygote , divides once or twice to form two or four diploid carpospores. From these, the tiny thread-like second generation shows that as with all Bangiales as Conchocelis is called stage created because it was once thought to be a so-called separate genus. Throughout the summer, more carpospores are continuously released, and the conchocelis stage also reproduces asexually by forming monospores under long-day conditions. In the short day (autumn) there is the formation of conchosporangia, in which meiosis , i.e. the transition to the haploid phase, takes place. The daughter cells resulting from this in four are only released as conchospores when the temperature drops to about 5 ° C. The next haploid generation can emerge from these after the host has sprouted again in December.
The transition from the formation of monospores to that of conchospores is one of the few known examples of a photoperiodic (day length dependent) regulation in red algae. It is apparently based on a phytochrome system as a photoreceptor .
Systematics
The species was first described in 1943 by Gilbert Morgan Smith and George Jacob Hollenberg as Porphyrella gardneri . The location of the type specimen is on the coast of the Monterey Peninsula in California. Since 1977 the species has been known as Porphyra gardneri (GMSmith & Hollenberg) MWHawkes. After molecular genetic investigations, Sandra C. Lindstrom placed them in the genus Pyropia in 2011 , at the same time numerous other former Porphyra species were spun off to Pyropia .
literature
- Robert Edward Lee: Phycology . 5th edition, Cambridge University Press, Cambridge 2018, pp. 107-109.
Individual evidence
- ↑ a b c Michael Guiry in Guiry, MD & Guiry, GM 2018. Pyropia gardneri . AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved August 22, 2018.
- ^ Judith E. Sutherland et al .: A new look at an ancient order: generic revision of the Bangiales (Rhodophyta) . Journal of Phycology 47 (5), 2011, pp. 1131-1151. doi : 10.1111 / j.1529-8817.2011.01052.x