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Blue light‐dependent monovalent anion uptake
Author(s) -
Quiñones Miguel A.,
Giráldez Nuria,
Witt Federico G.,
Aparicio Pedro J.
Publication year - 1997
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1997.tb03453.x
Subject(s) - flavin group , electron transport chain , ion transporter , chemistry , blue light , flavoprotein , ion , cotransporter , photochemistry , biophysics , membrane transport , membrane , biochemistry , biology , sodium , physics , organic chemistry , optics , enzyme
Blue light is one of the most important environmental signals regulating monovalent anion transport in plant cells. In the unicellular freshwater chlorophyte Monoraphidium braunii , blue light is essential for the activation of HCO 3 − , NO 3 − , NO 2 2 and Cl − transport systems. These anions are taken up when blue light is present but the uptake ceases when this radiation is suppressed, indicating that blue light is a switch signal for the monovalent anion transport system(s) of this alga. Similar results have been obtained in other green algae and higher plants. The action spectra for the uptake of NO 3 − and Cl − in M. braunii are very similar and resemble the absorption spectra of flavins or a combination of flavins and pterins. It is proposed that both anions share the same transport system(s). The uptake of monovalent anions consists of a cotransport with H + , thus producing alkalinization of the external medium. The time between the onset of blue light and the beginning of alkalinization can be as short as 2 s. Taken together, the results suggest that the photoreceptor mediating the blue light activation of monovalent anion uptake in this green alga is a plasma membrane‐bound flavoprotein.