Plant Physiological Adaptations Induced by Low Rates of Photosynthesis

1979 ◽  
Vol 34 (11) ◽  
pp. 932-935 ◽  
Author(s):  
Carl Fedtke
Keyword(s):  
Nitrogen Metabolism ◽  
Electron Flow ◽  
Low Light ◽  
Ecological Conditions ◽  
Photosynthetic Electron Flow ◽  
Partial Inhibition ◽  
Light Intensities ◽  
Physiological Adaptations ◽  
Rate Of Photosynthesis ◽  
Shade Adaptation

Abstract Among the adaptory responses of plants to different ecological conditions the adaptation to low light intensities is one of the most important. This response, known as “shade adaptation”, may, however, be similarly induced by decreasing the rate of photosynthesis in other ways. The partial inhibition of photosynthetic electron flow with herbicides has clearly been shown to induce shade- type plants; in the case of photosynthetic limitation by decreased CO2-availability only certain aspects of the shade-type metabolism - namely the changes occurring in the nitrogen metabolism - have been demonstrated.

Physiological Responses of Soybean (Glycine max)Plants to Metribuzin

Weed Science ◽  
1979 ◽  
Vol 27 (2) ◽  
pp. 192-195 ◽  
Author(s):  
C. Fedtke
Keyword(s):  
Glycine Max ◽  
Light Quality ◽  
Reducing Sugars ◽  
Electron Flow ◽  
Physiological Responses ◽  
Similar Response ◽  
Low Light ◽  
Photosynthetic Electron Flow ◽  
Induction Process ◽  
Soybean Plants

Soybean [Glycine max(L.) Merr. ‘Hark’] plants responded similarly to a sublethal application of metribuzin [2-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] or to low light intensities. Both treatments increased soluble amino acid, ATP, nitrate reductase, and nitrate levels (up to 67, 140, 190, and 10,000%, respectively) and decreased soluble reducing sugars (33%), malate levels (86%), and the chlorophyll a/b ratio (24%). The similar response of light-limited and of chemically photosynthesis-inhibited plants is thought to be induced by a carbohydrate stress or another parameter related to a decreased rate of photosynthetic electron flow. However, during the induction process in shaded plants, light quality might play an important role in some cases. The results obtained with metribuzin and soybean plants are compared to and discussed together with (a) the results obtained by other authors working withs-triazine herbicides and (b) results obtained with methabenzthiazuron [N-(benzothiazol-2-yl)-N,N′-dimethylurea] in earlier experiments.

Photosynthetic characteristics of a purple sulfur bacterium grown under different light intensities

1972 ◽  
Vol 18 (12) ◽  
pp. 1825-1828 ◽  
Author(s):  
M. Takahashi ◽  
K. Shiokawa ◽  
S. Ichimura
Keyword(s):  
Light Intensity ◽  
Photosynthetic Rate ◽  
Photosynthetic Characteristics ◽  
High Light ◽  
Bacteriochlorophyll A ◽  
Low Light ◽  
Purple Sulfur Bacterium ◽  
Light Intensities ◽  
Rate Of Photosynthesis ◽  
Structural Mechanisms

Photosynthetic characteristics of a purple sulfur bacterium, Chromatium, strain D, cultured under various light intensities were examined. With a decrease in the light intensity used for culture, the bacteriochlorophyll a content per unit cell nitrogen increased. Also, at low light intensities, the rate of photosynthesis (per unit bacteriochlorophyll a) was higher in samples grown under low light than in those grown under high light. These two responses to low light intensity are adaptations that ensure a high photosynthetic rate for the purple sulfur bacterium that usually occurs in a dimly lit environment. Possible chemical and structural mechanisms involved are discussed.

scholarly journals The desert green algae Chlorella ohadii thrives at excessive high light intensities by exceptionally enhancing the mechanisms that protect photosynthesis from photoinhibition

2021 ◽  
Author(s):  
Guy Levin ◽  
Sharon Kulikovsky ◽  
Varda Liveanu ◽  
Benjamin Eichenbaum ◽  
Ayala Meir ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Electron Flow ◽  
High Light ◽  
Low Light ◽  
Photosynthetic Organisms ◽  
Light Intensities ◽  
Protection Mechanisms ◽  
Desert Algae ◽  
Photo Damage ◽  
Fast Repair

AbstractAlthough light is the driving force of photosynthesis, excessive light can be harmful. One of the main processes that limits photosynthesis is photoinhibition (PI), the process of light-induced photo-damage. When the absorbed light exceeds the amount that is dissipated by photosynthetic electron flow and other processes, damaging radicals are formed that mostly inactivate photosystem II (PSII). Damaged PSII must be replaced by a newly repaired complex in order to preserve full photosynthetic activity. Chlorella ohadii is a green micro-alga, isolated from biological soil crusts in the desert that thrive under extreme high light and is highly resistant to PI. Therefore, C. ohadii is an ideal candidate for study the molecular protection mechanisms from PI. To charac-terize these protection mechanisms in C. ohadii, we compared thylakoids of cells that were grown under low light versus extreme high light intensities. C. ohadii were found to employ all three known PI protection mechanisms: i) performance of massive reduction of the PSII antenna size; ii) accumulate protective carotenoids; and iii) possess a very fast repair cycle of photo-damaged reaction center proteins. This work elucidated the molecular mechanisms of photoinhibition resistance in one of the most light-tolerant photosynthetic organisms and shows how photoinhibition protection mechanisms evolved to marginal conditions enabling photosynthesis-dependent life in severe habitats.One Sentence HighlightAnalysis of the photosynthetic properties of a desert algae that thrives at extreme high light in-tensities reveals how protection from photoinhibition is achieved by a remarkable enhancement of three protection mechanisms.

The mechanism of inhibition of photosynthesis by high partial pressures of oxygen in Chlorella

1966 ◽  
Vol 164 (996) ◽  
pp. 511-520 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Low Light ◽  
High Oxygen Partial Pressure ◽  
Carbon 14 ◽  
Light Intensities ◽  
Mechanism Of Inhibition ◽  
Partial Pressures ◽  
Rate Of Photosynthesis ◽  
Sugar Phosphates

The decrease in rate of photosynthesis of 14 CO 2 following a transition from 20 to 99.96% oxygen with 0.04% carbon dioxide was associated with a decrease in radioactivity of the sugar phosphates and an increase in that of glycollic acid. The effect of increasing the partial pressure of oxygen was greater at higher light intensities. At the highest light intensities used the inhibition became irreversible. When carbon-14 was incorporated into the sugar phosphates and the further metabolism of these compounds studied in carbon dioxide free conditions the main products in 20% oxygen were polyglucan and sucrose, but in the presence of high oxygen partial pressure they were glycollate and glycine. Radioactive glucose was fed in the presence of oxygen free of carbon dioxide. At low light intensities the main product was a polyglucan; at higher light intensitie sglycollic acid was formed and radioactive carbon dioxide was produced

Inhibition of photosynthesis by low oxygen concentrations

1981 ◽  
Vol 59 (5) ◽  
pp. 721-725 ◽  
Author(s):  
P. B. E. McVetty ◽  
D. T. Canvin
Keyword(s):  
Oxygen Concentration ◽  
High Light ◽  
Low Oxygen ◽  
Low Light ◽  
Light Intensities ◽  
Oxidation Reduction ◽  
Transport Chain ◽  
Rate Of Photosynthesis ◽  
Effect Of Oxygen ◽  
Temporary Inhibition

The effect of changing the oxygen concentration from 21 to 2% on photosynthesis of wheat, sunflower, and soybean was investigated. At low CO2 concentrations and low light intensities, a stimulation of photosynthesis was observed in 2% oxygen compared with the rate in 21% O2. At high CO2 concentrations and high light intensities, a temporary inhibition of photosynthesis was observed when the oxygen concentration was changed from 21 to 2%. In wheat and sunflower, this inhibition was observed at progressively lower CO2 concentrations as temperatures were decreased. In soybean only, a slight inhibition of photosynthesis was observed at higher temperatures. In some cases, especially in plants grown under a low light intensity, a long-lasting (> 45 min) inhibition of photosynthesis was observed. In most cases, however, the inhibition lasted only for several minutes and final rates of photosynthesis in 2% O2 were equal to or greater than the rate of photosynthesis in 21% O2. The stimulatory effect of oxygen on photosynthesis at high CO2 concentrations and high light intensities could possibly be due to a regulation of the oxidation–reduction state of the electron transport chain and the maintenance of phosphorylation.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

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