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Titolo:
PHOTOTROPISM IN SEAWEEDS - A REVIEW
Autore:
RICO JM; GUIRY MD;
Indirizzi:
UNIV OVIEDO,DEPT BIOL,C CATEDRATICO RODRIGO URIA S-N E-33071 OVIEDO SPAIN NATL UNIV IRELAND UNIV COLL GALWAY,MARTIN RYAN MARINE SCI INST GALWAYIRELAND
Titolo Testata:
Scientia marina
, volume: 60, anno: 1996, supplemento:, 1
pagine: 273 - 281
SICI:
0214-8358(1996)60:<273:PIS-AR>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
BLUE-LIGHT; MAIZE COLEOPTILES; NEGATIVE PHOTOTROPISM; CORN COLEOPTILES; STEM ELONGATION; BROWN ALGA; GROWTH; CALCIUM; RHODOPHYTA; INHIBITION;
Keywords:
PHOTOTROPISM; MACROALGAE; PHOTORECEPTOR; PHOTOMORPHOGENESIS; TRANSDUCTION; GROWTH RESPONSES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
96
Recensione:
Indirizzi per estratti:
Citazione:
J.M. Rico e M.D. Guiry, "PHOTOTROPISM IN SEAWEEDS - A REVIEW", Scientia marina, 60, 1996, pp. 273-281

Abstract

The existing literature on phototropism in marine macroalgae is reviewed. A phototropic response is a sequence of three different processes: reception of the directional light signal; transformation of the signal to a physiological response (transduction); and the production of directional growth response. The only available information about the photore ception of directional light comes from action spectra investigations. All the seaweeds thus Ear examined show a common pattern, with the maximum response occurring between 410-497 nm. A blue-light sensitive photoreceptor has therefore been postulated, and this photoreceptor is assumed to be a flavoprotein or a similar flavin molecule. The nature of the messen ger, the chemical responsible for triggering the growth response, is unknown in marine algae. Evidence for the Cholodny-Went theory of phototropic movement, which postulates movement by lateral auxin transport, is reviewed together with studies of the presence of higher plant growth regulators in seaweeds. Some evidence points to cAMP as a mediator through changes in membrane potential, and the effect of Ca2+ in the reversion of positive phototropism has been recently demostrated. The phosphorylation of an unknown 100-kDa protein hasalso been associated with the transduction of the directional signal. The growth response is produced by bulging, i.e., a change in the growth centre. This response is the result of changes in the conformationof the cell wall mediated by plasmatic microtubules. The similarity between this process and other morphogenetic processes in seaweeds is discussed. The phototropic response in seaweeds appears to be ecologically effective, provided that the light field in the sea is highly directional, the proportion of blue light increases with depth and growingtowards the light confers an advantage to upright thalli, while growing away from light is used by rhizoidal and attachment systems.

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Documento generato il 27/11/20 alle ore 10:44:25