Competition between the photosynthetic and the (chloro)respiratory electron transport chains in cyanobacteria, green algae and higher plants. Effect of heat stress |
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Authors: | F Lajkó A Kadioglu G Borbély G Garab |
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Institution: | (1) Biological Research Center, Hungarian Academy of Sciences, Szeged, Institute of Plant Biology, P.O. Box 521, H-6701, Hungary |
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Abstract: | By measuring the effect of cyanide on the flash-induced redox reactions of the cytochrome (cyt) b
6/f complex we carried out a comparative study in order to characterize the interaction between the photosynthetic and the respiratory
electron transport systems in cyanobacterial (Synechococcus sp. PCC 6301) and green algal (Chlamydomonas reinhardtii) cells, and in tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) protoplasts. We found that the addition of 1 mM KCN resulted in a significant acceleration of the
rereduction-rate of cyt f
+. This enhancement of the activity of the cyt b
6/f complex apparently occurred with the same mechanism in prokaryotes and eukaryotes, and its dependence on the concentration
of KCN in eukaryotes ruled out an origin in mitorespiration, superoxide dismutase and plastocyanin, strongly suggesting that
a cyanide-sensitive terminal oxidase, a putative component of chlororespiration, competes with photosystem 1 (PS1) for electrons
from the plastoquionone (PQ) pool. Concerning the physiological role of the competition between the (chloro)respiratory and
the photosynthetic electron transport systems, our data obtained with cyanobacterial and algal cells incubated at elevated
temperatures (30–50 °C) showed that the respiratory control over photosynthesis became significant in cells exposed to heat-stress.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | Chlamydomonas chloroplast KCN Nicotiana photosystem 1 protoplast Synechococcus temperature |
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