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22. Irradiance stress responses of gas exchange and antioxidant enzyme contents in pariparoba [Pothomorphe umbellata (L.) Miq.] plants
- Creator:
- Marchese, J. A., Mattana, R. S., Ming, L. C., Broetto, F., Vendramini, P. F., and Moraes, R. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- catalase, chlorophyll, oxidative stress, photosynthesis, shade plants, stomatal conductance, superoxide dismutase, and transpiration rate
- Language:
- Multiple languages
- Description:
- We evaluated the growth and development of the medicinal species Pothomorphe umbellata (L.) Miq. under different shade levels (full sun and 30, 50, and 70 % shade, marked as I100, I70, I50, and I30, respectively) and their effects on gas exchange and activities of antioxidant enzymes. Photosynthetically active radiation varied from 1 254 µmol m-2 s-1 at I100 to 285 µmol m-2 s-1 at I30. Stomatal conductance, net photosynthetic rate, and relative chlorophyll (Chl) content were maximal in I70 plants. Plants grown under I100 produced leaves with lower Chl content and signs of chlorosis and necrosis. These symptoms indicated Chl degradation induced by the generation of reactive oxygen species. Stress related antioxidant enzyme activities (Mn-SOD, Fe-SOD, and Cu/Zn-SOD) were highest in I100 plants, whereas catalase activity was the lowest. Hence P. umbellata is a shade species (sciophyte), a feature that should be considered in reforestation programs or in field plantings for production of medicinal constituents. and J. A. Marchese ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
23. Lack of the effect of superoxide dismutase and catalase on Na+,K+-ATPase activity in stunned rabbit hearts
- Creator:
- Peter Kaplán, Milena Matejovičová, Herijgers, P., and Flameng, W.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Experimentální medicína, kardiovaskulární fyziologie, volné radikály, cardiovascular physiology, free radicals, sodium pump, stunning, reperfusion, superoxide dismutase, catalase, 14, and 616-092
- Language:
- English
- Description:
- Reactive oxygen species (ROS) have been implicated in the mechanism of postischemic contractile dysfunction, known as myocardial stunning. In this study, we examined protective effects of antioxidant enzymes, superoxide dismutase (SOD) and catalase, against ischemia/reperfusion-induced cardiac dysfunction and inhibition of Na+,K+-ATPase activity. Isolated Langendorff-perfused rabbit hearts were subjected to 15 min of global normothermic ischemia followed by 10 min reperfusion. The hearts treated with SOD plus catalase did not show significant recovery of left ventricular (LV) end-diastolic pressure compared with untreated ischemic reperfused hearts. Treatment with antioxidants had no protective effects on developed LV pressure or its maximal positive and negative first derivatives (±LVdP/dt). Myocardial stunning was accompanied by significant loss in sarcolemmal Na+,K+-ATPase activity and thiol group content. Inhibition of enzyme activity and oxidation of SH groups were not prevented by antioxidant enzymes. These results suggest that administration of SOD and catalase in perfusate do not protect significantly against cardiac dysfunction in stunned rabbit myocardium., P. Kaplán, M. Matejovičová, P. Herijgers, W. Flameng., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
24. Leaf development and photosynthetic properties of three tropical tree species with delayed greening
- Creator:
- Cai, Z.-Q., Slot, M., and Fan, Z.-X.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Anthocephalus, ascorbate peroxidase, chlorophyll fluorescence, intercellular CO2 content, leaf dry mass per area, Litsea, net photosynthetic rate, stomatal conductance, and superoxide dismutase
- Language:
- Multiple languages
- Description:
- Leaf developmental patterns were characterized for three tropical tree species with delayed greening. Changes in the pigment contents, photosynthetic capacity, stomata development, photosystem 2 efficiency, rate of energy dissipation, and the activity of partial protective enzymes were followed in developing leaves in an attempt to elucidate the relative importance of various photoprotective mechanisms during leaf ontogeny. Big leaves of Anthocephalus chinensis, a fast-growing light demanding species, expanded following an exponential pattern, while relatively small leaves of two shade-tolerant species Litsea pierrei and Litsea dilleniifolia followed a sigmoidal pattern. The juvenile leaves of A. chinensis and L. pierrei contained anthocyanin located below the upper epidermis, while L. dilleniifolia did not contain anthocyanin. Leaves of A. chinensis required about 12 d for full leaf expansion (FLE) and photosynthetic development was delayed 4 d, while L. pierrei and L. dilleniifolia required 18 or 25 d for FLE and photosynthetic development was delayed 10 or 15 d, respectively. During the leaf development the increase in maximum net photosynthetic rate was significantly related to changes in stomatal conductance and the leaf maturation period was positively related to the steady-state leaf dry mass per area for the three studied species. Dark respiration rate of leaves at developing stages was greater, and pre-dawn initial photochemical efficiency was lower than that of mature leaves. Young leaves displayed greater energy dissipation than mature leaves, but nevertheless, the diurnal photoinhibition of young L. dilleniifolia leaves was higher than that of mature leaves. The young red leaves of A. chinensis and L. pierrei with high anthocyanin contents and similar diurnal photoinhibition contained more protective enzymes (superoxide dismutase, ascorbate peroxidase) than mature leaves. Consequently, red leaves may have higher antioxidant ability. and Z. Q. Cai, M. Slot, Z. X. Fan.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
25. Low night temperature-induced changes in photosynthesis and rubber accumulation in guayule (Parthenium argentatum Gray)
- Creator:
- Sundar, D. and Ramachandra Reddy, A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, fructose-6-phosphate, net photosynthetic rate, photosystems 1 and 2, proteins, rubber transferase, starch, saccharose, sucrose phosphate synthase, and superoxide dismutase
- Language:
- Multiple languages
- Description:
- Three-year-old plants of Parthenium argentatum Gray cv. 11591 grown under natural photoperiod were exposed for 60 d to low night temperature (LNT) of 15 °C (daily from 18:00 to 06:00). Effects of the treatment on net photosynthetic rates (PN), rubber accumulation, and associated biochemical traits were examined. LNT initially reduced PN with a parallel decline in the activities of ribulose-1,5-bisphosphate carboxylase, fructose bisphosphatase, and sucrose phosphate synthase for 20-30 d. Later, LNT enhanced PN and the activities of photosynthetic enzymes. Associated with high PN in LNT-treated guayule plants was a two-fold increase in rubber content and rubber transferase activity per unit of protein. The initial decrease in PN in LNT-treated guayule was associated with low content of chlorophyll (a+b), large starch accumulation, and higher ratio of glucose-6-phosphate/fructose-6-phosphate. Photosystem 2 activity in isolated chloroplasts was initially decreased, but increased after 30 d. There was a significant increase in the leaf soluble protein content in LNT-treated plants. Hence the photosynthetic performance of plants grown at 15 °C night temperature for 50 d was superior to those grown under natural photoperiod in all parameters studied. The high photosynthetic capacity may contribute to superior rubber yields under LNT. and D. Sundar, A. Ramachandra Reddy.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
26. Photoprotective effects of high level expression of C4 phosphoenolpyruvate carboxylase in transgenic rice during photoinhibition
- Creator:
- Jiao, D. M., Li, X., and Ji, B. H.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carbon assimilation, carbonic anhydrase, chlorophyll fluorescence, 3,3-dichloro-2-(dihydroxyphosphinoylmethyl)propenoate, enzymes scavenging active oxygen, malonyldialdehyde, Oryza, peroxidase, and superoxide dismutase
- Language:
- Multiple languages
- Description:
- With untransformed rice cv. Kitaake as control, the characteristics of carbon assimilation and photoprotection of a transgenic rice line over-expressing maize phosphoenolpyruvate carboxylase (PEPC) were investigated. The PEPC activity in untransformed rice was low, but the activity was stimulated under high irradiance or photoinhibitory condition. PEPC in untransformed rice contributed by about 5-10 % to photosynthesis, as shown by the application of the specific inhibitor 3,3-dichloro-2-(dihydroxyphosphinoylmethyl)propenoate (DCDP). When maize PEPC gene was introduced into rice, transgenic rice expressed high amount of maize PEPC protein and had high PEPC activity. Simultaneously, the activity of carbonic anhydrase (CA) transporting CO2 increased significantly. Thus the photosynthetic capacity increased greatly (50 %) under high CO2 supply. In CO2-free air, CO2 release in the leaf was less. In addition, PEPC transgenic rice was more tolerant to photoinhibition. Treating by NaF, an inhibitor of phosphatase, showed that in transgenic rice more phosphorylated light-harvesting chlorophyll a/b-binding complexes (LHC) moved to photosystem 1 (PS1) protecting thus PS2 from photo-damage. Simultaneously, the introduction of maize PEPC gene could activate or induce activities of the key enzymes scavenging active oxygen, such as superoxide dismutase (SOD) and peroxidase (POD). Hence higher PS2 photochemical efficiency and lower superoxygen anion (O2.-) generation and malonyldiadehyde (MDA) content under photoinhibition could improve protection from photo-oxidation. and D. M. Jiao, X. Li, B. H. Ji.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
27. Photosynthesis and photoinhibition in two differently coloured varieties of Oxalis triangularis - the effect of anthocyanin content
- Creator:
- Nielsen, S. L. and Simonsen, A.-M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, anthocyanin, ascorbate peroxidase, chlorophyll fluorescence, photoinhibition, photosynthesis, superoxide dismutase, and xanthophyll
- Language:
- Multiple languages
- Description:
- The purpose of this study was to clarify effects of anthocyanins on photosynthesis and photoinhibition in green and red leaves of Oxalis triangularis. Gas analysis indicated that green plants had the highest apparent quantum yield for CO2 assimilation [0.051 vs. 0.031 μmol(CO2) μmol-1(photon)] and the highest maximum photosynthesis [10.07 vs. 7.24 μmol(CO2) m-2 s-1], while fluorescence measurements indicated that red plants had the highest PSII quantum yield [0.200 vs. 0.143 μmol(e-) μmol-1(photon)] and ETRmax [66.27 vs. 44.34 μmol(e-) m-2 s-1]. Red plants had high contents of anthocyanins [20.11 mg g-1(DM)], while green plants had low and undetectable levels of anthocyanin. Red plants also had statistically significantly (0.05>p>0.01) lower contents of xanthophyll cycle components [0.63 vs. 0.76 mg g-1(DM)] and higher activities of the reactive oxygen scavenging enzyme ascorbate peroxidase [41.2 vs. 10.0 nkat g-1(DM)]. Anthocyanins act as a sunscreen, protecting the chloroplasts from high light intensities. This shading effect causes a lower photosynthetic CO2 assimilation in red plants compared to green plants, but a higher quantum efficiency of photosystem II (PSII). Anthocyanins contribute to photoprotection, compensating for lower xanthophyll content in red plants, and red plants are less photoinhibited than green plants, as illustrated by the Fv/Fm ratio. and S. L. Nielsen, A.-M. Simonsen
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
28. Photosynthesis, chlorophyll fluorescence, and antioxidant enzyme responses of invasive weed Mikania micrantha to Bemisia tabaci infestation
- Creator:
- Zhang, L. L. and Wen, D. Z.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, catalase, chlorophyll fluorescence, electron transport rate, glutathione, photochemical quenching, photosystem 2 efficiency, proline, and superoxide dismutase
- Language:
- Multiple languages
- Description:
- In a glasshouse, Bemisia tabaci infestation largely reduced response of photosynthesis to irradiance and CO2 concentration of Mikania micrantha compared with the non-infested control (C) ones. The maximum irradiance-saturated photosynthetic rate (Pmax) and saturation irradiance (SI) of the infested M. micrantha were only 21.3 % and 6.5 % of the C-plants, respectively. B. tabaci infestation led to the reduction of contents of chlorophyll and carotenoids in M. micrantha, which was accompanied with the decrease of actual photosystem 2 (PS2) efficiency (ΦPS2), efficiency of excitation energy capture by open PS2 reaction centres (Fv'/Fm'), electron transport rate (ETR), and photochemical quenching (qP). Moreover, superoxide dismutase and catalase activities significantly decreased while proline and glutathione contents significantly increased in infested M. micrantha. Hence B. tabaci infestation not only induced direct damage of photosynthetic apparatus but also altered the antioxidant enzymes activities in M. micrantha, which might as consequences accelerate senescence of this weed. and L. L. Zhang, D. Z. Wen.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29. Photosynthetic electron transport, photophosphorylation, and antioxidants in two ecotypes of reed (Phragmites communis Trin.) from different habitats
- Creator:
- Zhu, X. Y., Chen, G. C., and Zhang, C. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- antioxidant, ascorbate peroxidase, chloroplast, cyclic electron flow, Mg2+-ATPase, natural drought, photosystem 1 and 2 activities, stomatal resistance, superoxide dismutase, and transpiration rate
- Language:
- Multiple languages
- Description:
- We compared chloroplast photochemical properties and activities of some chloroplast-localised enzymes in two ecotypes of Phragmites communis, swamp reed (SR, C3-like) and dune reed (DR, C4-like) plants growing in the desert region of north-west China. Electron transport rates of whole electron transport chain and photosystem (PS) 2 were remarkably lower in DR chloroplasts. However, the electron transport rate for PS1 in DR chloroplasts was more than 90 % of the activity similar in the SR chloroplasts. Activities of Mg2+-ATPase and cyclic and non-cyclic photophosphorylations were higher in DR chloroplasts than in the SR ones. The activities of chloroplast superoxide dismutase (SOD) and ascorbate peroxidase (APX), both localised at or near the PS1 complex and serving to scavenge active oxygen around PS1, and the content of ascorbic acid, a special substrate of APX in chloroplast, were all higher in DR chloroplasts. Hence reed, a hydrophytic plant, when subjected to intense selection pressure in dune habitat, elevates its cyclic electron flow around PS1. In consequence, it provides extra ATP required by C4 photosynthesis. Combined high activities of active oxygen scavenging components in DR chloroplasts might improve protection of photosynthetic apparatus, especially PS1, from the damage of reactive oxygen species. This offers new explanation of photosynthetic performance of plant adaptation to long-term natural drought habitat, which is different from those, subjected to the short-term stress treatment or even to the artificial field drought. and X. Y. Zhu, G. C. Chen, C. L. Zhang.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
30. Photosynthetic rate, chlorophyll fluorescence parameters, and lipid peroxidation of maize leaves as affected by zinc deficiency
- Creator:
- Wang, H. and Jin, J. Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- photosystem 2, plastoquinone, stomatal conductance to H2O, superoxide dismutase, superoxygen anion radical, and Zea
- Language:
- Multiple languages
- Description:
- Pot trial in greenhouse was conducted using cumulic cinnamon soil from North China to study the effects of zinc deficiency on CO2 exchange, chlorophyll fluorescence, the intensity of lipid peroxidation, and the activity of superoxide dismutase (SOD) in leaves of maize seedlings. Zn deficiency resulted in a reduction of net photosynthetic rate and stomatal conductance to H2O. The maximum quantum efficiency of photosystem 2 (PS2) and the PS2 activity were depressed, while the pool size of the plastoquinone molecules was not affected by Zn deficiency. The content of super oxygen anion radical (O2.-) and the intensity of lipid peroxidation as assessed by malonyldialdehyde content in Zn-deficient leaves were higher than those in Zn-sufficient leaves. The activity of SOD increased with Zn application. The adverse influence of Zn-deficiency on the light stage of photosynthesis is probably one of possible reasons for the limitation of photosynthetic capacity in maize leaves. and H. Wang, J. Y. Jin.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public