Rhodochorton

Rhodochorton is a genus of filamentous red alga adapted to low light levels. It may form tufts or a thin purple "turf" up to 5 millimetres high. The filaments branch infrequently, usually at the tips.[2]

Rhodochorton
Rhodochorton purpureum
Scientific classification
(unranked): Archaeplastida
Division: Rhodophyta
Class: Florideophyceae
Order: Acrochaetiales
Family: Acrochaetiaceae
Genus: Rhodochorton
Nägeli[1]
Species
  • Rhodochorton entozoicum (Reinsch) De Toni
  • Rhodochorton kurilense Nagai
  • Rhodochorton lepadicola (Welwitsch) De Toni
  • Rhodochorton mesocarpum
  • Rhodochorton parkeri Gibson
  • Rhodochorton subsimplex (Harvey ex Agardh) De Toni

Morphology

In most species of Rhodochorton, the spore does not persist in the mature plant; instead, a basal web of filaments acts as a holdfast. Indeed, all Rhodochorton species have distinct basal threads, usually forming a disc, and upright threads, which are typically thinner.[2] Lateral branches usually occur at or near the top of the patent cell, and branching is concentrated towards the tips of threads.[2]

Ecology

The organism may encrust bare rock surfaces, or be epiphytic upon frondose algae - particularly Laminaria hyperborea.[3] It typically grows in the shadow of these larger algae, in the intertidal zone,[4] and its adaption to low light levels means it is also common in caves.[2] It reproduces in winter using tetrasporangia and don't bear any monosporangia.[5] Rhodochorton is typically marine, but R. investiens dwells in fresh water.[6] Sexual reproduction has never been observed.[7]

It suffers grazing pressure from gastropods and amphipods, but amazingly fragments of the algae are able to pass through the grazers' digestive tracts alive - grazing may actually form a mode of dispersal for the organism.[4]

Life history

Rhodochorton investiens displays a relatively simple life cycle for a red alga.[8]

In the Carposporophyte: a spermatium merges with a trichogyne (a long hair on the female sexual organ), which then divides to form carposporangia - which produce carpospores.

Carpospores germinate into gametophytes, which produce sporophytes. Both of these are very similar; they produce monospores from monosporangia "just below a cross wall in a filament"[8] and their spores are "liberated through apex of sporangial cell."[8]

The spores of a sporophyte produce tetrasporophytes. Monospores produced by this phase germinate immediately, with no resting phase, to form an identical copy of parent. Tetrasporophytes may also produce a carpospore, which germinates to form another tetrasporophyte.[8]

The gametophyte may replicate using monospores, but produces sperm in spermatangia, and "eggs"(?) in carpogonium.[8]

See also

The species in the genus Rhodothamniella closely resemble Rhodochorton

References
  1. Dixon, 1982:64
  2. Fritsch, F. E. (1945), The structure and reproduction of the algae, Cambridge: Cambridge Univ. Press, ISBN 978-0-521-05042-5, OCLC 223742770
  3. "Rhodochorton purpureum". www.horta.uac.pt. Retrieved 29 May 2018.
  4. Breeman, A. M.; Hoeksema, B. W. (1987), "Vegetative propagation of the red alga Rhodochorton purpureum by means of fragments that escape digestion by herbivores", Mar. Ecol. Prog. Ser., 35: 197–201, Bibcode:1987MEPS...35..197B, doi:10.3354/meps035197
  5. West, John A. (1969), "The Life Histories Of Rhodochorton Purpureum And R. Tenue In Culture", Journal of Phycology, 5 (1): 12–21, doi:10.1111/j.1529-8817.1969.tb02569.x, PMID 27097245.
  6. Swale, E. M. F.; Belcher, J. H. (April 1, 1963), "Morphological Observations on Wild and Cultured Material of Rhodochorton investiens (Lenormand) nov. comb. (Balbiania investiens (Lenorm.) Sirodot)", Annals of Botany, 27 (2): 282–290, doi:10.1093/oxfordjournals.aob.a083845
  7. West, John A. (1970), "A Monoecious Isolate Of Rhodochorton purpureum", Journal of Phycology, 6 (4): 368–370, doi:10.1111/j.0022-3646.1970.00368.x.
  8. Lee, R.E. (2008), Phycology, 4th edition, Cambridge University Press, ISBN 978-0-521-63883-8
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