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4881. Ultraviolet-B (280-320 nm) enhanced radiatíon induced changes in chlorophyll-protein complexes and polypeptide composition of chloroplasts in Vigna unguiculata seedlings grown at various temperatures

Creator:
Nedunchezhian, N., Anmamalainathen, K., and Kulandaivelu, G.
Format:
print
Type:
model:internalpart and TEXT
Subject:
Polyacrylamide and Electrophoresis
Language:
Multiple languages
Description:
The changes in pigment-protein composition of chloroplasts in Vigna unguiculata (L.) Walp seedlings grown under control and ultraviolet-B (UV-B) enhanced radiation at various temperatures were studied. The chlorophyll-protein (CP) complexes isolated from seedlings after 60 h of continuous UV-B enhanced radiation treatment showed temperature-dependent changes in their levels. At 10 ^C, well marked CPI, CP2a, CP47, CP2 and free pigment bands were seen in UV-B treated seedlings while control seedlings had no detectable green bands. UV-B enhanced radiation decreased the level of CPI, CP2a and CP2 complexes which was more pronounced at 20 and 30 °C than at 40 oC. The analysis of chloroplast polypeptides revealed a drastic decrease in the levels of 55, 47, 33, 25, 23, 22 and 17 kDa polypeptides in UV-B treated seedlings at 20 and 30 oC, and marginal decrease in the levels of 47, 43 and 16 kDa polypeptides at 40 ^C. In contrast to this, at 10 oC large increase in many polypeptides was noticed in UV-B treated seedlings.
Rights:
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4882. Ultraviolet-B induced changes in ultrastructure and D1/D2 proteins in cyanobacteria synechococcus sp. PCC 7942

Creator:
Chauhan, Sanjay, Pandey, Ritu, and Singhal, Gauri S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carotenoids, cell shape, chlorophyll, phycocyanin, and thylakoid
Language:
Multiple languages
Description:
Effects of ultraviolet-B (UV-B) irradiation on ultrastructure, total cellular protein, and PS2 proteins D1 and D2 of Synechococcus sp. PCC 7942 cells was studied. The scanning electron micrographs showed UV-B radiation induced bending of the cells. The transmission electron micrographs revealed disorganization and shift in thylakoid lamellar structure to one side of the cell. The cellular phycocyanin/chlorophyll ratio decreased with increasing UV-B treatment and due to this the colour of cells turned light-green. No apparent change in total cellular proteins was evident, but the contents of two major proteins of PS2, D1 and D2, showed decline due to UV-B irradiation, although to different extent. and Sanjay Chauhan, Ritu Pandey, Gauri S. Singhal.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4883. Ultraviolet-B radiation (280-315 nm) invoked antioxidant defence systems in Vigna unguiculata (L.) Walp. and Crotalaria juncea L.

Creator:
Selvakumar, V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
ascorbate-glutathione cycle, ascorbate oxidase and peroxidase, catalase, dehydroascorbate reductase, glutathione transferase, monodehydroascorbate reductase, oxidative stress, peroxidase, and superoxide dismutase
Language:
Multiple languages
Description:
A crop legume Vigna unguiculata L. (Walp.) and a wild legume Crotalaria juncea L. were evaluated for their relative responses to the oxidative stress injury induced by various doses of UV-B radiation (UV-B, 280-315 nm; 0, 1.0, 1.4, 4.7, and 6.0 kJ m-2 d-1). A dose-dependent damage in lipid peroxidation was determined as an index of membrane injury caused by UV-B. The impact was significantly higher in V. unguiculata than in C. juncea. The specific activities of superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase increased directly proportional to UV-B doses. However, the activities of these enzymes were significantly higher in V. unguiculata than in C. juncea indicating that V. unguiculata was inflicted with more severe oxidative stress injury under UV-B. In C. juncea the glutathione reductase and ascorbate oxidase activities were 35 and 40 % greater than in V. unguiculata, respectively. Further, the non-enzymatic antioxidants ascorbate and glutathione, and their reduced/oxidizes ratios in C. juncea were much greater than V. unguiculata indicating C. juncea has an inherently greater antioxidative potential than V. unguiculata. Thus C. juncea is better adapted to oxidative stress than V. unguiculata by means of efficient cellular antioxidant mechanisms helping to combat the photooxidative stress injury elicited by UV-B.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4884. Ultraviolet-B radiation or heat cause changes in photosynthesis, antioxidant enzyme activities and pollen performance in olive tree

Creator:
Koubouris, G. C., Kavroulakis, N., Metzidakis, I. T., Vasilakakis, M. D., and Sofo, A.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, klimatické změny, ozon, olivovník evropský, photosynthesis, climate changes, ozone, Olea europaea, Kréta (Řecko : ostrov), Crete (Greece), abiotic stress, lipid peroxidation, pollen germination, 2, and 581
Language:
Multiple languages
Description:
The present study attempts to determine how some physiological and reproductive functions of olive tree (Olea europaea L., cv. Koroneiki) respond to enhanced UV-B radiation or heat. Enhanced UV-B radiation was applied to (1) three-year-old potted plants in an open nursery (corresponded to ca. 16% ozone depletion), and (2) in vitro cultured pollen samples (220 μmol m-2 s-1, PAR = 400-700 nm + UV-B at 7.5, 15.0, or 22.5 kJ m-2 d-1). Potted olive plants were also subjected to high temperature (38 +- 4°C) for 28 h to mimic heat levels regularly measured in olive growing areas. A significant effect of UV-B on photosynthetic rate was observed. However, enhanced UV-B radiation did affect neither chlorophyll nor carotenoid content, supporting previous reports on hardiness of the photosynthetic apparatus in olive. Increased superoxide dismutase activity was observed in UV-B-treated olive plants (+ 225%), whereas no effect was found in the plants under heat stress. Neither UV-B and nor heat did affect H2O2 accumulation in the plant tissues. However, the same treatments resulted in enhanced lipid peroxidation (+ 18% for UV-B and + 15% for heat), which is likely linked to other reactive oxygen species. The increased guaiacol peroxidase activity observed in both treatments (+ 32% for UV-B and + 49% for heat) is related to the defense against oxidative membrane damage. The observed reduction in pollen germination (20-39%) and tube length (11-44%) could have serious implications on olive yields, especially for low fruit-setting cultivars or in years and environments with additional unfavorable conditions. UV-B and heat effects described here support the hypothesis that plant response to a given stressor is affected by the overall context and that a holistic approach is necessary to determine plant strategies for climate change adaptation., G. C. Koubouris, N. Kavroulakis, I. T. Metzidakis, M. D. Vasilakakis, A. Sofo., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4885. Underestimate of PS2 efficiency in the field due to high leaf temperature resulting from leaf clipping and its amendment

Creator:
Weng, J.-H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, leaf clip, leaf temperature, irradiance, Oryza, photosystem 2 efficiency, and rice
Language:
Multiple languages
Description:
Chlorophyll fluorescence parameter Fv/Fm, an indicator of the maximum efficiency of PS2, is routinely measured in the field with plant leaves darkened by leaf clips. I found that on a sunny day of subtropical summer, the Fv/Fm ratio was often underestimated because of a large F0 value resulted from a high leaf temperature caused by clipping the leaf under high irradiance, especially for long (e.g. 20 min) duration. This phenomenon may overestimate the down-regulation of PS2 efficiency under high irradiance. When leaf temperature was lower than 40 °C, the F0 level of rice leaves under clipping remained practically unchanged. However, F0 increased drastically with leaf temperature rising over 40 °C. In most measurements, no significant difference in Fm was found between rice leaves dark-adapted by leaf clips for 10 min and for 20 min. Therefore, shading leaf clips to prevent a drastic increase of leaf temperature, using F0 measured immediately after the leaf being darkened to calculate Fv/Fm, as well as shortening the duration of leaf clipping are useful means to avoid an underestimate of Fv/Fm.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4886. Underestimated chlorophyll a fluorescence measurements on Buxus microphylla red winter leaves

Creator:
Peng, J. G., Jiang, X. R., Xu, J., Guo, L., Gao, R. F., and Liu, Y.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
obecná botanika, general botany, boxwood, evergreen species, palisade tissue, red carotenoids, spongy tissue, 2, and 581
Language:
Multiple languages
Description:
Leaves under stressful conditions usually show downregulated maximum quantum efficiency of photosystem II [inferred from variable to maximum chlorophyll (Chl) a fluorescence (Fv/Fm), usually lower than 0.8], indicating photoinhibition. The usual method to evaluate the degree of photoinhibition in winter red leaves is generally by measuring the Fv/Fm on the red adaxial surface. Two phenotypes of overwintering Buxus microphylla ‘Wintergreen’ red leaves, with different measuring site and leaf thickness, were investigated in order to elucidate how red pigments in the outer leaf layer affected the Chl a fluorescence (Fv/Fm) and photochemical reflectance index. Our results showed that the Fv/Fm measured on leaves with the same red surface, but different leaf thickness, exhibited a slightly lower value in half leaf (separated upper and lower layers of leaves by removing the leaf edge similarly as affected by winter freezing and thawing) than that in the intact leaf (without removing the leaf edge), and the Fv/Fm measured on the red surface was significantly lower than that on the inner or backlighted green surface of the same thickness. Our results suggest that the usual measurement of Fv/Fm on red adaxial surface overestimates the actual degree of photoinhibition compared with that of the whole leaf in the winter., J. G. Peng, X. R. Jiang, J. Xu, L. Guo, R. F. Gao, Y. Liu., and Obsahuje použitou literaturu
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4888. Uniconazole (S-3307) induced protection of Abelmoschus ssculentus L. against cadmium stress

Creator:
Purohit, S. and Singh, V. P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
biomass, chlorophyll, detoxification, growth, and Hill reaction activity
Language:
Multiple languages
Description:
In Abelmoschus esculentus L. uniconazole brought about a marked decrease in cadmium-induced loss of chlorophyll and Hill reaction activity, but it did not completely prevent cadmium toxicity. and S. Purohit, V. P. Singh.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4889. Unintended effects of genetic transformation on photosynthetic gas exchange, leaf reflectance and plant growth properties in barley (Hordeum vulgare L.)

Creator:
Sun, C. X., Yuan, F., Zhang, Y. L., Cui, Z. B., Chen, Z. H., Chen, L. J., and Wu, Z. J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, genetic modification, leaf area, light-use efficiency, reflectance index, reflectance spectra, stomatal limitation, transgenic plants, water-use efficiency, 2, and 58
Language:
Multiple languages
Description:
Characterization of different component processes of photosynthesis is useful to understand the growth status of plants and to discover possible unintended effects of genetic modification on photosynthesis in transgenic plants. We focused on the changes in photosynthetic gas-exchange properties, reflectance spectra, and plant growth traits among groups of different transgenic barley T1 (TolT1) and its isogenic controls (TolNT1), TolT1, and group of its own transgenic progenies T2 (TolT2), TolNT1 and its wild type (WT), respectively. Gas-exchange measurements showed that only the net photosynthetic rate (P N) and the light-use efficiency (LUE) differed significantly between TolT1 and TolT2 with no obvious changes of other characteristics. Reflectance measurements indicated that the reflectance ratio was sensitive to identify the differences between two barley groups. Differences in reflectance expressed on an index basis depended on barley groups. The relationship between LUE and the photochemical reflectance index (PRI) at a leaf level among different barley groups of WT, TolNT1, TolT1 and TolT2 did not changed obviously. The differences in the total leaf area per plant (LA) between WT and TolNT1 as well as between TolT1 and TolT2 were significant. This study finally provided a plausible complex explanation for the unintended effects of genetic transformation on photosynthesis-related properties in barley at different levels. Furthermore, it was concluded that the photosynthesis-related properties of transgenic plants based on gas exchange, leaf reflectance, and plant growth measurements responded to the same environment in a more different way between two subsequent generations than to the processes of the gene insertion by Agrobacterium and associated tissue culture., C. X. Sun ... [et al. ]., and Obsahuje bibliografii
Rights:
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4890. Universal chlorophyll equations for estimating chlorophylls a, b, c, and d and total chlorophylls in natural assemblages of photosynthetic organisms using acetone, methanol, or ethanol solvents

Creator:
Ritchie, R. J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Acaryochloris, algorithms, error structure, Phaeodactylum, phaeophytin, Rhodomonas, spectrophotometric determination, and Synechococcus
Language:
Multiple languages
Description:
A universal set of equations for determining chlorophyll (Chl) a, accessory Chl b, c, and d, and total Chl have been developed for 90 % acetone, 100 % methanol, and ethanol solvents suitable for estimating Chl in extracts from natural assemblages of algae. The presence of phaeophytin (Ph) a not only interferes with estimates of Chl a but also with Chl b and c determinations. The universal algorithms can hence be misleading if used on natural collections containing large amounts of Ph. The methanol algorithms are severely affected by the presence of Ph and so are not recommended. The algorithms were tested on representative mixtures of Chls prepared from extracts of algae with known Chl composition. The limits of detection (and inherent error, ±95 % confidence limit) for all the Chl equations were less than 0.03 g m-3. The algorithms are both accurate and precise for Chl a and d but less accurate for Chl b and c. With caution the algorithms can be used to calculate a Chl profile of natural assemblages of algae. The relative error of measurements of Chls increases hyperbolically in diluted extracts. For safety reasons, efficient extraction of Chls and the convenience of being able to use polystyrene cuvettes, the algorithms for ethanol are recommended for routine assays of Chls in natural assemblages of aquatic plants.
Rights:
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