Stimulation of photosynthetic electron transport in a salt-tolerant plant by high chloride concentrations

Nature ◽  
1982 ◽  
Vol 298 (5873) ◽  
pp. 483-485 ◽  
Author(s):  
Christa Critchley
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Salt Tolerant ◽  
Tolerant Plant ◽  
High Chloride ◽  
Chloride Concentrations ◽  
Stimulation Of

scholarly journals Plastid terminal oxidase requires translocation to the grana stacks to act as a sink for electron transport

2018 ◽  
Vol 115 (38) ◽  
pp. 9634-9639 ◽  
Author(s):  
Piotr Stepien ◽  
Giles N. Johnson
Keyword(s):  
Electron Transport ◽  
Brassica Species ◽  
Photosynthetic Electron Transport ◽  
Terminal Oxidase ◽  
Significant Activity ◽  
Salt Tolerant ◽  
Sensitive Species ◽  
Tolerant Plants ◽  
Eutrema Salsugineum ◽  
Plastid Terminal Oxidase

The plastid terminal oxidase (PTOX) has been shown to be an important sink for photosynthetic electron transport in stress-tolerant plants. However, overexpression studies in stress-sensitive species have previously failed to induce significant activity of this protein. Here we show that overexpression of PTOX from the salt-tolerant brassica species Eutrema salsugineum does not, alone, result in activity, but that overexpressing plants show faster induction and a greater final level of PTOX activity once exposed to salt stress. This implies that an additional activation step is required before activity is induced. We show that that activation involves the translocation of the protein from the unstacked stromal lamellae to the thylakoid grana and a protection of the protein from trypsin digestion. This represents an important activation step and opens up possibilities in the search for stress-tolerant crops.

scholarly journals The effects of oxygen solubility and high concentrations of salts on photosynthetic electron transport in chloroplast membranes

1984 ◽  
Vol 218 (2) ◽  
pp. 539-545 ◽  
Author(s):  
B Thomasset ◽  
J N Barbotin ◽  
D Thomas
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Potassium Citrate ◽  
Potassium Ferricyanide ◽  
O2 Evolution ◽  
Oxygen Solubility ◽  
Chloroplast Membranes ◽  
Ferricyanide Reduction ◽  
High Concentrations ◽  
Stimulation Of

Chloroplast membranes were isolated in different media containing Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid] and high concentrations of sorbitol (0.33 M), potassium citrate (0.75 M) or Na2SO4 (1.0 M). Due to the complexity of the media, the oxygen solubility is strongly modified by high concentrations of salts (oxygen solubility for 0.33 M-sorbitol, 0.21 mmol/litre; for 0.75 M-potassium citrate, 0.121 mmol/litre; and for 1.0 M-Na2SO4, 0.112 mmol/litre). The knowledge of these values is necessary to interpret the rate of O2 evolution. For thylakoids isolated in ‘sorbitol buffer’ and then tested in high concentrations of potassium citrate, a slight stimulation of O2 evolution is observed (143-173 mumol of O2/h per mg of chlorophyll a) with potassium ferricyanide as electron acceptor. When we monitor the potassium ferricyanide reduction, no stimulation of electron transport is obtained even if the observed phenomenon is identical with the Photosystem-II oxygen evolution. In the same experiments no stimulation of the photophosphorylation was recorded, but when thylakoids are directly isolated in 0.75 M-potassium citrate, O2 evolution, ferricyanide reduction and photophosphorylation are inhibited by high concentrations of salts. The behaviour of thylakoids seems to be influenced by their initial treatment.

scholarly journals Plant Response to Saline Substrates VIII. Regulation of Ion Concentrations in Salt-Sensitive and Halophytic Species

1966 ◽  
Vol 19 (5) ◽  
pp. 741 ◽  
Author(s):  
H Greenway ◽  
A Gunn ◽  
DA Thomas
Keyword(s):  
Hordeum Vulgare ◽  
Phaseolus Vulgaris ◽  
Plant Response ◽  
Salt Tolerant ◽  
Sensitive Species ◽  
Ion Concentrations ◽  
Whole Plants ◽  
High Chloride ◽  
Chloride Concentrations

Concurrent uptake and export of ions were measured in a very salt-sensitive species, Phaseolus vulgaris, and in a halophyte, Atriplex. In plants with high chloride and sodium � concentrations, the whole plants, shoots, and older leaves exported only a small percentage of previously absorbed ions. However, chloride retranslocation from older leaves was appreciable in plants of low chloride concentrations. Similar results were obtained previously for a salt-tolerant non-halophyte (Hordeum vulgare). Thus these halophytes and non-halophytes do not differ in the characteristics rneasured.

Superoxide-and Ethane-Formation in Subchloroplast Particles: Catalysis by Pyridinium Derivatives

1980 ◽  
Vol 35 (9-10) ◽  
pp. 770-775 ◽  
Author(s):  
E. F. Elstner ◽  
H. P. Fischer ◽  
W. Osswald ◽  
G. Kwiatkowski
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Redox Potentials ◽  
Light Reaction ◽  
Pyridinium Bromide ◽  
Superoxide Formation ◽  
Fatty Acid Peroxidation ◽  
Chlorophyll Bleaching ◽  
Ethane Formation

Abstract Oxygen reduction by chloroplast lamellae is catalyzed by low potential redox dyes with E′0 values between -0 .3 8 V and -0 .6 V. Compounds of E′0 values of -0 .6 7 V and lower are inactive. In subchloroplast particles with an active photosystem I but devoid of photosynthetic electron transport between the two photosystems, the active redox compounds enhance chlorophyll bleaching, superoxide formation and ethane production independent on exogenous substrates or electron donors. The activities of these compounds decrease with decreasing redox potential, with one exception: 1-methyl-4,4′-bipyridini urn bromide with an E′0 value of lower -1 V (and thus no electron acceptor of photosystem I in chloroplast lamellae with intact electron transport) stimulates light dependent superoxide formation and unsaturated fatty acid peroxidation in sub­ chloroplast particles, maximal rates appearing after almost complete chlorophyll bleaching. Since this activity is not visible with compounds with redox potentials below -0 .6 V lacking the nitrogen atom at the 1-position of the pyridinium substituent, we assume that 1 -methyl-4,4′-bi-pyridinium bromide is “activated” by a yet unknown light reaction.

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