ISSN:
1432-2048
Keywords:
Chlorophyll fluorescence
;
Chloroplast (electron transport)
;
Electron transport
;
Oxygen evolution
;
Photosynthesis (electron transport)
;
Photosystem II
;
Zea (electron transport)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The relationship between the redox state of the primary electron acceptor of photosystem II (QA) and the rate of O2 evolution in isolated mesophyll chloroplasts from Zea mays L. is examined using pulse-modulated chlorophyll a fluorescence techniques. A linear relationship between photochemical quenching of chlorophyll fluorescence (qQ) and the rate of O2 evolution is evident under most conditions with either glycerate 3-phosphate or oxaloacetate as substrates. There appears to be no effect of the transthylakoid pH gradient on the rate of electron transfer from photosystem II into QA in these chloroplasts. However, the proportion of electron transport occurring through cyclic-pseudocyclic pathways relative to the non-cyclic pathway appears to be regulated by metabolic demand for ATP. The majority of non-photochemical quenching in these chloroplasts at moderate irradiances appeared to be “energy”-dependent quenching.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00397649
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