Influence of Bleaching Herbicides on Chlorophyll and Carotenoids

1979 ◽  
Vol 34 (11) ◽  
pp. 1047-1051 ◽  
Author(s):  
Karl-Josef Kunert ◽  
Peter Böger
Keyword(s):  
Electron Transport ◽  
Oxygen Evolution ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
Pigment Content ◽  
Photosynthetic Oxygen Evolution ◽  
Direct Inhibition ◽  
Scenedesmus Acutus ◽  
Photosynthetic Oxygen ◽  
Chlorophyll Formation

Abstract Over 24 and 48 hour cultivation periods the influence of SAN 9789 (norflurazon), EMD-IT 5914 (difunon) and fluridone on growth, photosynthetic oxygen evolution and pigment content of the green alga Scenedesmus acutus was determined. Four effects were observed: a) Both carotenoid and chlorophyll formation were inhibited. b) Carotenoids were destroyed in the presence of air, but not nitrogen. The level of chlorophyll, however, did not change. c) β- (and α-) carotene was markedly decreased in the presence of oxygen. d) Photosynthetic oxygen evolution was decreased with the disappearance of carotenoids. These effects, which are accompanied by reduced growth, are believed to represent primary herbicidal modes of action. The decrease of oxygen evolution is not due to a direct inhibition of photosynthetic electron transport by the herbicides applied.

scholarly journals TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

2020 ◽  
Author(s):  
Azeez Beebo ◽  
Ahmad Zia ◽  
Christopher R. Kinzel ◽  
Andrei Herdean ◽  
Karim Bouhidel ◽  
...  
Keyword(s):  
Electron Transport ◽  
Oxygen Evolution ◽  
Photosynthetic Electron Transport ◽  
Chloroplast Envelope ◽  
Photosynthetic Oxygen Evolution ◽  
Wild Type ◽  
Thylakoid Lumen ◽  
Photosynthetic Oxygen ◽  
Osmotic Treatment ◽  
Envelope Membranes

SUMMARYPhotosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of Arabidopsis thaliana. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both thylakoid and envelope membranes. Mutants lacking TIP1;2 and/or TIP2;1 did not display a macroscopic phenotype when grown under standard conditions. The mutant chloroplasts and thylakoids underwent less volume changes than the corresponding wild type preparations upon osmotic treatment and in the light. Significantly reduced rates of photosynthetic electron transport were obtained in the mutant leaves, with implications on the CO2 fixation rates. However, electron transport rates did not significantly differ between mutants and wild type when isolated thylakoids were examined. Less acidification of the thylakoid lumen was measured in mutants thylakoids, resulting in a slower induction of delta pH-dependent photoprotective mechanisms. These results identify TIP1;2 and TIP2;1 as chloroplast proteins and highlight their importance for osmoregulation and optimal photosynthesis. A third aquaporin, TIP1;1, is present in the chloroplast envelope, and may play role in photosynthesis under excessive light conditions, as based on the weak photosynthetic phenotype of its mutant.

Photosynthesis and nitrogenase activity in the blue-green alga Gloeocapsa

1974 ◽  
Vol 20 (12) ◽  
pp. 1633-1637 ◽  
Author(s):  
J. R. Gallon ◽  
T. A. LaRue ◽  
W. G. W. Kurz
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Evolution ◽  
Green Alga ◽  
Photosynthetic Pigments ◽  
Nitrogenase Activity ◽  
Photosynthetic Oxygen Evolution ◽  
Blue Green Alga ◽  
Temporal Separation ◽  
Young Culture ◽  
Photosynthetic Oxygen

In a young culture, photosynthetic-oxygen evolution by Gloeocapsa is at a low level while nitrogenase activity is at its greatest. When the culture ages, there is a rapid increase in photosynthetic pigments and oxygen evolution, and nitrogenase activity decreases. The temporal separation of nitrogen fixation and photosynthesis may serve to protect nitrogenase from oxygen denaturation.

Blue Light-Enhanced Photosynthetic Oxygen Evolution from Liposome-Bound Photosystem II Particles; Possible Role of the Xanthophyll Cycle in the Regulation of Cyclic Electron Flow Around Photosystem II?

1995 ◽  
Vol 50 (1-2) ◽  
pp. 61-68 ◽  
Author(s):  
W. I. Gruszecki ◽  
K. Strzałka ◽  
A. Radunz ◽  
J. Kruk ◽  
G. H. Schmid
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Xanthophyll Cycle ◽  
Red Light ◽  
Photosynthetic Oxygen Evolution ◽  
Reaction Centre ◽  
Ps Ii ◽  
Photosynthetic Oxygen ◽  
Β Carotene

Abstract Light-driven electron transport in liposome-bound photosystem II (PS-II) particles be­tween water and ferricyanide was monitored by bare platinum electrode oxymetry. The modi­fication of the experimental system with the exogenous quinones α-tocopherol quinone ( α-TQ) or plastoquinone (PQ) resulted in a pronounced effect on photosynthetic oxygen evolution. The presence of α-tocopherolquinone ( α-TQ) in PS-II samples decreased the rate of red light-induced oxygen evolution but increased the rate of green light-induced oxygen evolution. Blue light applied to the assay system in which oxygen evolution was saturated by red light resulted in a further increase of the oxygen signal. These findings are interpreted in terms of a cyclic electron transport around PS-II, regulated by an excitation state of β-carotene in the reaction centre of PS-II. A mechanism is postulated according to which energetic coupling of β-carotene in the reaction centre of PS-II and that of other antenna carotenoid pigments is regulated by the portion of the xanthophyll violaxanthin, which is under control of the xanthophyll cycle.

The Bleaching Effect of the Diphenyl Ether Oxyfluorfen

Weed Science ◽  
1981 ◽  
Vol 29 (2) ◽  
pp. 169-173 ◽  
Author(s):  
K. J. Kunert ◽  
P. Böger
Keyword(s):  
Spinacia Oleracea ◽  
Diphenyl Ether ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Oxygen Evolution ◽  
Bleaching Effect ◽  
Activation Time ◽  
Scenedesmus Acutus ◽  
Diphenyl Ethers ◽  
Photosynthetic Oxygen ◽  
Ethane Formation

The diphenyl ether, oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], exerts a very strong and rapid bleaching effect upon intact microalgae such asScenedesmus acutus. Carotenoids, and subsequently chlorophylls, are destroyed concurrently with ethane formation and inhibition of photosynthetic oxygen evolution. These herbicidal effects are not observed before an activation time of approximately 2 h, during which photosynthetic electron transport is necessary. Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] inhibits oxyfluorfen activity during this activation time, but not thereafter. Isolated spinach chloroplasts (Spinacia oleracea‘Atlanta’) evolve ethane after a light-incubation phase in the presence of oxyfluorfen as well as paraquat (methylviologen, 1,1′-dimethyl-4,4′-bipyridinium ion). Depending on their chemical constitution, diphenyl ethers apparently act differently and multifunctionally. The effects described for oxyfluorfen are believed to represent the primary mode of action of bleaching diphenyl ethers.

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