Response of senescing wheat leaves to ultraviolet a light: Changes in energy transfer efficiency and PS II photochemistry

Joshi, Padmanava; Biswal, Basanti; Kulandaivelu, G.; Biswal, U. C.

doi:10.1007/bf01219339

Cited by 20 publications

(10 citation statements)

References 25 publications

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“…), superoxide radicals (O 2 -) or their protonated form (HO 2 ), hydroxyl radicals (HO -) or hydrogen peroxide (H 2 O 2 ) are all capable of lipid peroxidation. UV radiation appears to be one of the most powerful ways to induce cell peroxidation (Tyrrell, 1991), as has been demonstrated for a number of higher plants exposed to both UVA (Joshi et al, 1994) and UVB (Saradhi, Arora & Prasad, 1995). These oxidation processes invariably have detrimental effects on PUFAs, and in fact this loss may be used as a direct measure of the lipid peroxidation process.…”

Section: Effects On Carbohydrates Proteins Lipids Amino Acids and mentioning

confidence: 98%

UV‐induced changes in phytoplankton cells and its effects on grazers

1997

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1. This review addresses the effects of UV‐radiation on the morphology and biochemistry of phytoplankton and the potential effects on grazers. 2. UVA and UVB radiation inhibit the uptake of inorganic nutrients in phytoplankton. Reduced rates of ammonium and nitrate uptake in marine diatoms, and reduced uptake of phosphorus in freshwater flagellates are reported. The effects on cell stoichiometry are not settled. 3. UVA and UVB radiation promote increased cell volumes owing to a decoupling between the photosynthetic processes and cell division. Loss or inactivation of flagellae and loss of motility are also reported for a number of phytoplankton species. 4. UVA and UVB radiation may affect major biochemical constituents. Accumulation of intracellular, photosynthetic products (lipids or carbohydrates) is a common, although not unique, property of UV‐stressed algae. Fatty acid (FA) profiles seem susceptible to UV radiation. A relative increase of short‐chained, and a decrease in polyunsaturated FA (PUFA) are reported. The important membrane FA like eicosapentaenoic acid (EPA, 20 : 5ω3) and docosahexaenoic acid (DHA, 22 : 6ω3) seem particularly susceptible, owing to lipid peroxidation or reduced biosynthesis. 5. UV‐related responses are highly dependent on taxonomy, cell‐cycle stage, nutrient‐limitation and the UV : PAR (photosynthetic active radiation)‐ratio. 6. Nutrient deficiency, cell size, cell wall properties and FA can all have significant impacts on grazers. Thus the reported effects on cell morphology and biochemical constituents could have profound effects on grazers and energy transfer in aquatic foodwebs.

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Section: Effects On Carbohydrates Proteins Lipids Amino Acids and mentioning

confidence: 98%

UV‐induced changes in phytoplankton cells and its effects on grazers

1997

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“…Light is a well-known stress factor of plants and the mechanisms of its harmful effects are well characterized in the photosynthetically active (400-700 nm) and UV-B (290-320) spectral ranges (3,4,9). Although previous literature data indicate that UV-A (320-400 nm) radiation also exerts harmful effects on photosynthetic organisms and may target PSII (15)(16)(17), the mechanism of UV-A damage was not studied and understood in detail.…”

Section: The Primary Target Of Uv-a Is Psiimentioning

confidence: 99%

Inhibition of Photosynthetic Electron Transport by UV-A Radiation Targets the Photosystem II Complex¶

Turcsányi

Vass

2000

Photochem Photobiol

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We have studied the inhibition of photosynthetic electron transport by UV-A (320-400 nm) radiation in isolated spinach thylakoids. Measurements of Photosystem II (PSII) and Photosystem I activity by Clark-type oxygen electrode demonstrated that electron flow is impaired primarily in PSII. The site and mechanism of UV-A induced damage within PSII was assessed by flash-induced oxygen and thermoluminescence (TL) measurements. The flash pattern of oxygen evolution showed an increased amount of the S0 state in the dark, which indicate a direct effect of UV-A in the water-oxidizing complex. TL measurements revealed the UV-A induced loss of PSII centers in which charge recombination between the S2 state of the water oxidizing complex and the semireduced Q(A)- and Q(B)- quinone electron acceptors occur. Flash-induced oscillation of the B TL band, originating from the S2Q(B)- recombination, showed a decreased amplitude after the second flash relative to that after the first one, which is consistent with a decrease in the amount of Q(B)- relative to Q(B) in dark adapted samples. The efficiency of UV-A light in inhibiting PSII electron transport exceeds that of visible light 45-fold on the basis of equal energy and 60-fold on the basis of equal photon number, respectively. In conclusion, our data show that UV-A radiation is highly damaging for PSII, whose electron transport is affected both at the water oxidizing complex, and the binding site of the Q(B) quinone electron acceptor in a similar way to that caused by UV-B radiation.

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“…The reduction in the foliar carbohydrate content and the inhibition of shoot growth under UV-A stress were reported by other authors [7][8][9][10], who attributed this response to a damaging effect on the photosynthetic machinery, cell division, and/or plant genome. The present data (Tables 2, 3) can support this interpretation.…”

Section: Discussionmentioning

confidence: 71%

“…UV-A is an environmental stress factor for the cotton plant [8]. Relatively little is known about plant responses to it [7][8][9][10], neither cultivar nor tolerance responses were investigated. The present study was conducted to test whether two Egyptian cotton cultivars, Giza 45 and Giza 86, differ in sensitivity to UV-A (366 nm).…”

Section: Introductionmentioning

confidence: 99%

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Tolerance Responses of Two Cotton Cultivars Exposed to Ultraviolet-A: Photosynthetic Performance and Some Chemical Constituents

Ebrahim

2005

Russ J Plant Physiol

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Stress tolerance of two Egyptian cotton cultivars ( Gossypium barbadense L.) (Giza 45 and Giza 86) exposed to various doses (40, 80, 160, and 320 min) of artificial ultraviolet-A (UV-A) radiation (366 nm) was investigated. Seed germination of cv. Giza 86 was promoted at 40 min, progressively inhibited at 80 and 160 min, and completely suppressed at 320 min irradiation. However, seed germination of cv. Giza 45 was not promoted but inhibited by UV-A light and stopped at the dose of 160 min. In contrast to seed germination, seedling growth of cv. Giza 86 was negatively stressed even at 40 min-dose. UV-A radiation reduced leaf carbohydrate content and shoot growth of both cultivars, but the response was comparatively higher in cv. Giza 45. UV-A radiation decreased chlorophyll (Chl) and carotenoid contents in parallel with an increase in the Chl a/b ratio, diminished Hill reaction activity, and quenched Chl a fluorescence independent of the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, suggesting an inhibitory effect on both the water-splitting system and electron transport from the primary to the secondary acceptors of photosystem II (PSII) (acceptor side). UV-A radiation also decreased the ratio of unsaturated to saturated fatty acids in thylakoid membranes, thus indicating that the inhibition of PSII activity was followed by lipid peroxidation and changes in thylakoid membrane fluidity. These changes reflect the disturbance of structure, composition, and functioning of the photosynthetic apparatus, as well as the sensitivity of PSII to UV-A stress. Both cultivars developed adaptive mechanisms for damage alleviation involving the accumulation of flavonoids, total lipids, and total soluble proteins, as well as development of smaller and thicker leaf blades. Since cv. Giza 86 showed comparatively higher level of adaptation, it tolerates UV-A stress more successful than cv. Giza 45.

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Response of senescing wheat leaves to ultraviolet a light: Changes in energy transfer efficiency and PS II photochemistry

Cited by 20 publications

References 25 publications

UV‐induced changes in phytoplankton cells and its effects on grazers

UV‐induced changes in phytoplankton cells and its effects on grazers

Inhibition of Photosynthetic Electron Transport by UV-A Radiation Targets the Photosystem II Complex¶

Tolerance Responses of Two Cotton Cultivars Exposed to Ultraviolet-A: Photosynthetic Performance and Some Chemical Constituents

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