Photoelectron transport ability of chloroplast thylakoid membranes treated with NO donor SNP: Changes in flash oxygen evolution and chlorophyll fluorescence

Nitric Oxide ◽  
2011 ◽  
Vol 24 (2) ◽  
pp. 84-90 ◽  
Author(s):  
Radka Vladkova ◽  
Anelia G. Dobrikova ◽  
Ranjeet Singh ◽  
Amarendra N. Misra ◽  
Emilia Apostolova
Keyword(s):  
Chlorophyll Fluorescence ◽  
Oxygen Evolution ◽  
Thylakoid Membranes ◽  
No Donor

Carotenoids and Photosystem II Characteristics of Upper and Lower Halves of Leaves Acclimated to High Light

1996 ◽  
Vol 23 (6) ◽  
pp. 669 ◽  
Author(s):  
WW Iii Adams ◽  
B Demmig-Adams ◽  
DH Barker ◽  
S Kiley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Total Energy ◽  
Xanthophyll Cycle ◽  
Lower Surface ◽  
Thylakoid Membranes ◽  
High Light ◽  
Pigment Composition ◽  
Light Gradient

Acclimation of the leaves or stems of four succulent species to different light environments and to the light gradient across high light-acclimated tissues was examined through measurements of chlorophyll fluorescence and characterisation of the pigment composition of the thylakoid membranes. Whereas the total amounts of light striking the upper (sun-exposed) and lower (self-shaded) surfaces were quite different, resulting in a much smaller pool of the xanthophyll cycle carotenoids in the lower halves of high light-acclimated tissues, the conversion state of the xanthophyll cycle (the degree to which violaxanthin is converted to antheraxanthin and zeaxanthin) was similar throughout the tissues during exposure to natural sunlight. Under full sunlight, less than 25% of the light absorbed by the upper surface was utilised through photosynthesis, with the majority of the remaining excitation energy being dissipated thermally. In contrast, a considerably greater fraction of the light absorbed by the lower surface was utilised in photosynthesis, ranging from one-third to more than two-thirds of the total energy absorbed.

Mechanism of Non-Photochemical Chlorophyll Fluorescence Quenching. II. Resolution of Rapidly Reversible Absorbance Changes at 530 Nm and Fluorescence Quenching by the Effects of Antimycin, Dibucaine and Cation Exchanger, A23187

1995 ◽  
Vol 22 (2) ◽  
pp. 239 ◽  
Author(s):  
N Mohanty ◽  
AM Gilmore ◽  
HY Yamamoto
Keyword(s):  
Chlorophyll Fluorescence ◽  
Fluorescence Quenching ◽  
Cation Exchanger ◽  
Thylakoid Membranes ◽  
Chlorophyll Fluorescence Quenching ◽  
Absorbance Changes ◽  
Energy Dependent ◽  
The Relationship ◽  
Effect Of Inhibitors ◽  
Exchange Properties

The putative relationship between the light-induced absorbance increase at 530 nm (ΔA530), the so-called light-scattering change, and non-photochemical chlorophyll fluorescence quenching (NPQ) was examined by the effect of inhibitors. Antimycin at a low concentration (350 nM) completely inhibited fluorescence quenching while only partially inhibiting A530. This effect was independent of the mode of thylakoid energisation and preinduction of violaxanthin de-epoxidation. Dibucaine at 20 FM abolished NPQ but had little effect on ΔA530. Moreover, the light-induced ΔA530 signal was present even in the absence of de-epoxidised xanthophylls. The cation exchanger A23187 blocked the development of NPQ as well as relaxed fluorescence quenching at steady state without involving a major portion of ΔA530. Thus, the relationship between energy-dependent A530 changes and fluorescence quenching was non-linear under all conditions tested. The light-induced absorbance increase at 530 nm, therefore, is insufficient for NPQ. The differential effects of inhibitors are explained schematically, depicting three phases for NPQ: (a) formation of zeaxanthin and antheraxanthin by the xanthophyll cycle; (b) formation of a state reflected by A530 that is induced by the transthylakoid ApH, possibly involving aggregation of LHCII; and (c) fluorescence quenching by the combined effect of both steps and by the H+-cation exchange properties of thylakoid membranes.

The sun-exposed peel of apple fruit has a higher photosynthetic capacity than the shaded peel

2007 ◽  
Vol 34 (11) ◽  
pp. 1038 ◽  
Author(s):  
Li-Song Chen ◽  
Lailiang Cheng
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Oxygen Evolution ◽  
Photosynthetic Capacity ◽  
Light Exposure ◽  
Calvin Cycle ◽  
Apple Fruit ◽  
Thermal Dissipation ◽  
The Sun ◽  
Significant Difference

To determine whether the sun-exposed peel of apple fruit has a higher photosynthetic capacity than the shaded peel, fruit peel samples were taken in both early July and early September from the exterior part of the canopy of mature ‘Liberty’/M.9 trees for measuring oxygen evolution, key enzymes and metabolites involved in photosynthesis, and chlorophyll fluorescence. Compared with the shaded peel, the sun-exposed peel had higher light-saturated oxygen evolution rate and higher light saturation point, but lower apparent and true quantum yields. The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, glyceraldehyde-3-phosphate dehydrogenase, phosphoribulokinase, stromal fructose-1,6-bisphosphatase, ADP-glucose pyrophosphorylase and sucrose-phosphate synthase (SPS) were higher in the sun-exposed peel than in the shaded peel on both sampling dates except that no significant difference was found in SPS activity between the two peel types in September. No significant difference was detected in the concentration of key metabolites (G6P, F6P, G1P, and PGA) between the sun-exposed peel and the shaded peel, suggesting that the response of the key enzymes to light exposure is well coordinated. Chlorophyll fluorescence quenching analysis showed that the sun-exposed peel had higher PSII quantum efficiency than the shaded peel at each given PFD, which resulted mainly from the higher photochemical quenching coefficient (qP). The sun-exposed peel had higher thermal dissipation capacity, as indicated by larger NPQ and Fo quenching, than the shaded peel at high PFD. In conclusion, the sun-exposed peel of apple fruit has higher activities of the Calvin cycle enzymes and higher rate of electron transport, leading to higher photosynthetic O2 evolution capacity. It appears that the acclimation of the Calvin cycle activities, thermal dissipation, and electron transport in apple peel are well coordinated in response to light exposure.

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