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1812. Characteristics of chlorophyll fluorescence and membrane-lipid peroxidation during senescence of flag leaf in different cultivars of rice
- Creator:
- Jiao, Demao, Ji, Benhua, and Li, Xia
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- active oxygen, catalase, malonyldialdehyde, Oryza, peroxidase, photoinhibition, photooxidation, photosystem 2, premature ageing, superoxide dismutase, and xanthophyll cycle
- Language:
- Multiple languages
- Description:
- With japonica rice 98-08, indica hybrids Shanyou 63, Gangyou 881, and X07S/Zihui 100, and sub-species hybrid Peiai 64S/9311 as materials, chlorophyll (Chl) content, Chl a fluorescence parameters, and membrane lipid peroxidation in flag leaf were measured at late developmental stages under natural conditions. Fv/Fm, qP, ΦPS2, and electron transport rate gradually decreased while qN increased conversely. Excessive photon energy led to the accumulation of active oxygen (O2-), H2O, malonyldialdehyde, and products of membrane lipid peroxidation, and resulted in reduced Chl content and early ageing subsequent to the photooxidation during flag leaf senescence. There was obvious diversification of these parameters among rice cultivars. In comparison with japonica cv. 98-08 (tolerant to photooxidation), Fv/Fm decreased in indica cv. Shanyou 63 (susceptible to photooxidation) with greater accumulation of active oxygen and a sharp drop in Chl content, which resulted in "yellowish" early ageing, and affected the filling and setting of rice grains. The mechanism for premature ageing in indica rice was related to irradiance and temperature at filling stages. On a sunny day at above 25 °C, the reaction centre of photosystem 2 (PS2) exhibited a dynamic change on reversible inactivation. Under the intense irradiance at noon, PS2 function in indica rice exhibited obvious down-regulation and photoinhibition. Under intense irradiance with lowered temperatures, PS2 resulted in photo-damage and early ageing, related to the degradation of PS2-D1 protein and the inhibition of endogenous protection systems such as the xanthophyll cycle and enzymes scavenging active oxygen. Hence for high-yield breeding, based on a good plant-type and utilising heterosis and tolerance of photooxidation, the selection of japonica rice or a sterile line with the japonica genotype as female is a strategy worthy of consideration. and Demao Jiao, Benhua Ji, Xia Li.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1813. Characteristics of in vivo nitrate reduction in the CAM plant Notonia grandiflora DC.
- Creator:
- Balakumar, T., Thangavel, M., and Paliwal, K.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Characteristics of in vivo nitráte reductase (NR, EC 1.6.6.1) activity in leaf tissue of the crassulacean acid metabolism (CAM) plant Notonia grandiflora DC. were determined. The pH optimum for the enzyme was 7.0. Among the five low molecular mass solvents tested, n-propanol was more effective in promoting NR activity. Supply of 1.0 % (v/v) M-propanol along with 0.5 % Triton X-100 was the most appropriate assay condition to bring about maximum NR activity (NRA), that was proportionally enhanced with duration of the incubation and mass of the leaf tissue. Leaf fragments of 2 to 4 mm slice width had maximal NRA. The highest NRA was obtained with 200 mM of nitráte supplied in the infiltration medium. NRA was higher in fully expanded, mature leaves than in tender and senescing leaves. The cellular nitráte content was strongly positively correlated with NRA in leaves of various physiological ages. The NRA/N03’ content ratio (index of nitráte utilization efQciency) was the highest for the tender leaves and the lowest for the senescing leaves. However, maximum total titratable acidity (malate production) was obtained for the fully expanded mature leaves in comparison with the other leaves. A positive and significant correlation (r = 0.92) was obtained between nitráte reduction and titratable acid content. The results are indicative of a possible role of nitráte reduction in the regulation of noctumal acid production in the CAM plants.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1814. Characteristics of photosynthetic apparatus in Mn-starved maize leaves
- Creator:
- Jiang, C.-D., Gao, H.-Y., and Zou, Q.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, net photosynthetic rate, photoinhibition, violaxanthin, violaxanthin de-epoxidase, xanthophyll cycle, Zea, and zeaxanthin
- Language:
- Multiple languages
- Description:
- The effects of Mn-deficiency on CO2 assimilation and excitation energy distribution were studied using Mn-starved maize leaves. Mn-deficiency caused about 70 % loss in the photon-saturated net photosynthetic rate (PN) compared to control leaves. The loss of PN was associated with a strong decrease in the activity of oxygen evolution complex (OEC) and the linear electron transport driven by photosystem 2 (PS2) in Mn-deficienct leaves. The photochemical quenching of PS2 (qP) and the maximum efficiency of PS2 photochemistry (Fv/Fm) decreased significantly in Mn-starved leaves under high irradiance, implicating that serious photoinhibition took place. However, the 'high-energy' fluorescence quenching (qE) decreased, which was associated with xanthophyll cycle. The results showed that the pool of de-epoxidation components of the xanthophyll cycle was lowered markedly owing to Mn deficiency. Linear electron transport driven by PS2 de-creased significantly and was approximately 70 % lower in Mn-deficient leaves than that in control, indicating less trans-thylakoid pH gradient was built in Mn deficient leaves. We suggest that the decrease of non-radiative dissipation depending on xanthophyll cycle in Mn-starved leaves is a result of the deficiency of trans-thylakoid pH gradient. and C. D. Jiang, H. Y. Gao, Q. Zou.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1815. Characteristics of sun- and shade-adapted populations of an endangered plant Primulina tabacum Hance
- Creator:
- Liang, K. M., Lin, Z. F., Ren, H., Liu, N., Zhang, Q. M., Wang, J., Wang, Z. F., and Guan, L. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, cave microenvironment, chloroplast ultrastructure, ecophysiological trait, light adaptation, morphological structure, and Primulina tabacum Hance
- Language:
- Multiple languages
- Description:
- Primulina tabacum Hance is an endangered perennial herb distributed in calcium-rich and nitrogen-limited soil of the karst limestone areas in southern China. The morphological, ultrastructural, and physiological traits were determined for P. tabacum populations growing in three different environment conditions: twilight zone of a cave (site TZ, extremely low light intensity), at a cave entrance (site EZ, low light intensity), and in an open area (site OA, high light intensity). At site OA, P. tabacum plants were exposed to high light (635 μmol m-2 s-1 of mean daily photosynthetically active radiation) with drought stress, and expressed traits to minimize light capture and water loss. Compared to plants at sites EZ and TZ, those at site OA had thicker leaves with higher densities of stomata and pubescence, higher palisade/spongy ratio, higher light-saturated rate of net photosynthetic rate (Pmax), higher biomass, higher non-photochemical quenching coefficient (NPQ), and higher light saturation point (LSP) but fewer grana per chloroplast and less thylakoid stacking per granum. In contrast, P. tabacum growing at the cave vicinities: EZ (mean daily irradiance 59 μmol m-2 s-1) and TZ (mean daily irradiance 11 μmol m-2 s-1) showed typical shade-adapted characteristics for optimum light capture. The presence of sun- and shade-adapted characteristics indicates that P. tabacum has different strategies to cope with different environments but whether these strategies reflect genetic selection or phenological plasticity is yet to be determined. Such variability in physiological and morphological traits is important for the survival of P. tabacum in heterogeneous light conditions. and K. M. Liang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1816. Characterization of different isoforms of the light-harvesting chlorophyll a/b complexes of photosystem II in bamboo
- Creator:
- Jiang, Z. H., Peng, Z. H., Gao, Z. M., Liu, C., and Yang, C. H.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, bamboo, isoform, light-harvesting complexes, 2, and 58
- Language:
- Multiple languages
- Description:
- The major light-harvesting chlorophyll (Chl) a/b complexes of photosystem II (LHCIIb) play important roles in energy balance of thylakoid membrane. They harvest solar energy, transfer the energy to the reaction center under normal light condition and dissipate excess excitation energy under strong light condition. Many bamboo species could grow very fast even under extremely changing light conditions. In order to explain whether LHCIIb in bamboo contributes to this specific characteristic, the spectroscopic features, the capacity of forming homotrimers and structural stabilities of different isoforms (Lhcb1-3) were investigated. The apoproteins of the three isoforms of LHCIIb in bamboo are overexpressed in vitro and successfully refolded with thylakoid pigments. The sequences of Lhcb1 and Lhcb2 are similar and they are capable of forming homotrimer, while Lhcb3 lacks 10 residues in the N terminus and can not form the homotrimeric structure. The pigment stoichiometries, spectroscopic characteristics, thermo- and photostabilities of different reconstituted Lhcbs reveal that Lhcb3 differs strongly from Lhcb1 and Lhcb2. Lhcb3 possesses the lowest Qy transition energy and the highest thermostability. Lhcb2 is the most stable monomer under strong illumination among all the isoforms. These results suggest that in spite of small differences, different Lhcb isoforms in bamboo possess similar characteristics as those in other higher plants., Z. H. Jiang ... [et al.]., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1817. Characterization of isolated photosystem I from Halomicronema hongdechloris, a chlorophyll f-producing cyanobacterium
- Creator:
- Li, Y., Vella, N., and Chen, M.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- sinice, Cyanophyta, far-red light photoacclimation, oxygenic photosynthesis, red-shifted chlorophyll, 2, and 581
- Language:
- Multiple languages
- Description:
- Halomicronema hongdechloris is a chlorophyll (Chl) f-producing cyanobacterium. Chl f biosynthesis is induced under far-red light, extending its photosynthetically active radiation range to 760 nm. In this study, PSI complexes were isolated and purified from H. hongdechloris, grown under white light (WL) and far-red light (FR), by a combination of density gradient ultracentrifugation and chromatographic separation. WL-PSI showed similar pigment composition as that of Synechocystis 6803, using Chl a in the reaction center. Both Chl a and f were detected in the FR-PSI, although Chl f was a minor component (~8% of total Chl). The FR-PSI showed a maximal fluorescence emission peak of 750 nm at 77 K, which is red-shifted ~20 nm compared to the 730 nm recorded from the WL-PSI. The absorption peaks of P700 for WLPSI and FR-PSI were 699 nm and 702 nm, respectively. The function of Chl f in FR-PSI is discussed., Y. Li, N. Vella, M. Chen., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1818. Characterization of photosynthesis of Populus euphratica grown in the arid region
- Creator:
- Chen, Y. P., Chen, Y. N., Li, W. H., and Xu, C. C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- drought stress, intercellular CO2 concentration, stomatal conductance, and transpiration rate
- Language:
- Multiple languages
- Description:
- Net photosynthetic rate (PN), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate (E), water use efficiency (WUE), and stomatal limitation (Ls) of Populus euphratica grown at different groundwater depths in the arid region were measured. gs of the trees with groundwater depth at 4.74 m (D4) and 5.82 m (D5) were lower and a little higher than that at 3.82 m (D3), respectively. Compared with C i and Ls of the D3 trees, Ci decreased and Ls increased at 4.74 m, however, Ci increased and Ls decreased at D5. Hence photosynthetic reduction of P. euphratica was attributed to either stomatal closure or non-stomatal factors depending on the groundwater depths in the plant locations. PN of the D3 trees was significantly higher than those at D4 or D5. The trees of D4 and D5 did not show a significant difference in their PN, indicating that there are mechanisms of P. euphratica tolerance to mild and moderate drought stress. and Y. P. Chen ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1819. Characterization of photosynthetic apparatus of pea chlorophyll mutants and their heterotic F1 hybrids with standard genotype (cv. Torsdag)
- Creator:
- Vaishlya, O. B., Ladygin, V. G., Sokolov, V. A., and Semenova, G. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra of chloroplast pigments, carotenoids, glyceraldehyde phosphate dehydrogenase, palisade eand spongy parenchyma, phosphoenolpyruvate carboxylase, photophosphorylation, photosystems 1 and 2, Pisum sativum, and ribulose-1,5-bisphosphate carboxylase
- Language:
- Multiple languages
- Description:
- In comparison to cv. Torsdag, in leaves of low-productive Pisum sativum L. chlorophyll mutants the decrease in chlorophyll content was caused by the decrease in cell number per unit volume. Qualitative changes in activities of photosystem (PS) 1 in mutant M2004, and quantitative changes of PS1 and PS2 in mutants M2004 and M2014 and in hybrids were also found. However, the activity of ribulose-1,5-bisphosphate carboxylase (RuBPC) in M2014, and those of RuBPC and glyceraldehyde phosphate dehydrogenase in M2004 and hybrids were higher than in cv. Torsdag. The hybrids inherited the normal structure of photosynthetic apparatus of standard genotype in parallel with the compensatory gene complex of M2004, which was expressed at many levels of organization. This may be the basis of hybrid vigour in this case. and O. B. Vaishlya ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1820. Characterization of photosynthetic pathway of plant species growing in the eastern Tibetan plateau using stable carbon isotope composition
- Creator:
- Li, M. C., Liu, H. Y., Yi, X. F., and Li, L. X.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- adaption to environment, alpine meadow, species differences, water-use efficiency, and δ13C values
- Language:
- Multiple languages
- Description:
- The photosynthetic pathway of plant species collected at Menyuan, Henan, and Maduo sites, east of Tibetan Plateau, China, during the growing season were studied using stable carbon isotopes in leaves. The 232 samples leaves analyzed belonged to 161 species, 30 families, and 94 genera. The δ13C values (from -24.6 to -29.2 ‰) indicated that all the considered species had a photosynthetic C3 pathway. The absence of plant species with C4 photosynthetic pathway might be due to the extremely low air temperature characterizing the Tibetan Plateau. The average δ13C value was significantly (p<0.05) different between annuals and perennials at the three considered study sites. Hence the longer-lived species had greater water-use efficiency (WUE) than shorter-lived species, that is, longer-lived species are better adapted to the extreme environmental conditions of the Tibetan Plateau. and M. C. Li ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public