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11. Effects of cadmium stress upon activities of antioxidative enzymes, photosynthetic rate, and production of phytochelatins in leaves and chloroplasts of wheat cultivars differing in yield potential

Creator:
Ahmad, I., Naeem, M., Khan, N. A., and Samiullah
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
ascorbate peroxidase, ATP-sulfurylase, catalase, glutathione, glutathione reductase, stomatal conductase, superoxide dismutase, Triticum, and water use efficiency
Language:
Multiple languages
Description:
We tested the mode of action of Cd on photosynthesis and activities of ATP-sulfurylase (ATP-S), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), and on contents of phytochelatins (PCs) and glutathione (GSH) in two cultivars of wheat (Triticum aestivum L.) PBW-343 and WH-542 differing in yield potential. Cd treatment increased Cd content and photosynthetic activity in PBW-343 more than in WH-542. The activities of APX, GR, ATP-S, and synthesis of PCs and GSH were also increased by Cd, but the CAT and SOD activities were inhibited in both the cultivars. The efficient functioning of antioxidative enzymes, production of PCs and GSH, helped in counteracting the effects of Cd namely in PBW-343, protected photosynthetic ability, and increased the tolerance to Cd. and I. Ahmad ... [et al.].
Rights:
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12. Effects of water deficit on photosynthetic rate and osmotic adjustment in tetraploid wheats

Creator:
Rekika, D., Nachit, M. M., Araus, J. L., and Monneveux, P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
drought tolerance, durum wheat, intercellular CO2 concentration, leaf water status, Triticum, water stress, and wild emmer wheat
Language:
Multiple languages
Description:
Osmotic adjustment, accumulation of soluble saccharides, and photosynthetic gas exchange were studied in five durum wheat (Triticum turgidum L. var. durum) and one wild emmer wheat (Triticum turgidum L. var. dicoccoïdes) cultivars of contrasting drought tolerance and yield stability. Soil water contents (SWC) were 100, 31, 20, and 12 % of maximum capillary capacity. Under mild water stress (SWC 31 to 20 %), osmotic adjustment capacity and high accumulation of saccharides were found in cv. Cham1, a high yielding and drought tolerant cultivar, and in var. dicoccoïdes, while lowest values were noted in the durum wheat landraces Oued-Zenati and Jennah-Khotifa. Under more severe water stress (SWC 12 %), the cv. Cham1 maintained higher net photosynthetic rate (PN) than other genotypes. The observed changes in the ratio intercellular/ambient CO2 concentration (ci/ca) indicated that under mild and severe water stress, the decrease in PN was mainly due to stomatal and non-stomatal factors, respectively. and D. Rekika ... [et al.].
Rights:
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13. Function of node unit in photosynthate distribution to root in higher plants

Creator:
Osaki, M., Shinano, T., Yamada, M., and Yamada, S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Glycine, Helianthus, Lycopersicon, node unit, photosynthate translocation, phytomer, phyllotaxy, phyton, source-sink relationship, and Triticum
Language:
Multiple languages
Description:
Leaf-root interaction is a critical factor for plant growth during maturation and activity of roots is maintained by a sufficient supply of photosynthates. To explain photosynthate distribution among organs in field crops, the node unit hypothesis is proposed. One node unit consists of a leaf and an upper adventitous root, as well as the axillary organs and the lower adventitious root, which is adjacent to one node. Using 14C as tracer, the carbon distribution system has been clarified using spring wheat, soybean, tomato, and potato. The interrelationship among organs from the strongest to the weakest is in the following order: (1) within the node unit > (2) between the node unit in the same or adjacent phyllotaxy > (3) in the main root or apical organs, which are adjacent to the node unit. Within the node unit, 14C assimilated in the leaf on the main stem tended to distribute to axillary organs in the same node unit. The 14C assimilated in the leaf of axillary organs tended to distribute within the axillary organs, including adventitious roots in the axillary organ and then translocated to the leaf on the main leaf of the same node unit. In different organs of the node unit in the same or adjacent phyllotaxy, 14C assimilated in the leaf on the main stem was also distributed to the organs (node unit) belonging to the same phyllotaxy in dicotyledons, while in monocotyledons, the effect of phyllotaxy on 14C distribution was not clear. Among roots/apical organs and node unit, 14C assimilated in the upper node unit was distributed to apical organs and 14C assimilated in the lower node unit was distributed to roots. Thus the node unit hypothesis of photosynthate distribution among organs is very important for understanding the high productivity of field crops. and M. Osaki ... [et al.].
Rights:
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14. Gas exchange of spring barley and wheat grown under mild water shortage

Creator:
Łoboda, T.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Hordeum, intercellular CO2 concentration, photosynthesis, stomatal conductance, and Triticum
Language:
Multiple languages
Description:
During mild water stress (decrease of full water capacity from 60 to 35 %) net photosynthetic rate (PN) of four spring barley and wheat genotypes was about twice lower than that for unstressed plants and was mainly limited by non-stomatal factors. Availability of CO2 from intercellular spaces did not change significantly when stomatal conductance (gs) decreased from 0.25-0.35 to 0.15-0.20 mol(H2O) m-2 s-1. There may be two main processes leading to similar intercellular CO2 concentration (ci) in stressed and unstressed seedlings despite of twice lower PN under mild water stress: (a) lower diffusion of CO2 through stomata represented by lower gs, (b) lower consumption of CO2 by photosynthetic apparatus of stressed plants. Last factor is partially pronounced by lower response of PN to ci observed for stressed than for control plants.
Rights:
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15. Ionic and osmotic effects of salinity on single-leaf photosynthesis in two wheat cultivars with different drought tolerance

Creator:
Muranaka, S., Shimizu, K., and Kato, M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, cultivar differences, O2 evolution, photochemical activity, SPAD, and Triticum
Language:
Multiple languages
Description:
The effects of iso-osmotic salinity and drought stresses on leaf net photosynthetic rate (PN) in two wheat (Triticum aestivum L.) cultivars BR 8 and Norin 61, differing in drought tolerance, were compared. In drought-sensitive Norin 61, the decline of PN was larger than that in drought-tolerant BR 8. Under NaCl treatment, PN decreased in two phases similarly in both cultivars. In the first phase, photosynthetic depression was gradual without any photochemical changes. In the second phase, photosynthetic depression was rapid and accompanied with a decline of the energy conversion efficiency in photosystem 2 (ΦPS2). Our observations suggest that the osmotic factor may induce a gradual depression of photosynthesis due to stomatal closure under both stress treatments. However, under NaCl treatment, a ionic factor (uptake and accumulation of excess Na+) may have direct effects on electron transport and cause more severe photosynthetic depression. The drought tolerance mechanism of BR 8 was insufficient to maintain single-leaf photosynthesis under salinity. and S. Muranaka, K. Shimizu, M. Kato.
Rights:
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16. Mercury inhibits the activity of the NADPH:protochlorophyllide oxidoreductase (POR)

Creator:
Lenti, K., Fodor, F., and Böddi, B.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll formation, fluorescence emission spectra, heavy metal, Hg, protochlorophyllide, Triticum, and wheat
Language:
Multiple languages
Description:
The effect of Hg++ was studied on the arrangement and photoactivity of NADPH:protochlorophyllide oxidoreductase (POR) in homogenates of dark-grown wheat (Triticum aestivum L.) leaves. 77 K fluorescence emission spectra of the homogenates were recorded before and after the irradiation of the homogenates and the spectra were deconvoluted into Gaussian components. The mercury treatment caused a precipitation of the membrane particles, which was followed by a remarkable decrease of the fluorescence yield. 10-3 M Hg++ decreased the ratio of the 655 nm-emitting protochlorophyllide (Pchlide) form to the 633 nm-emitting form. 10-2 M Hg++ shifted the short wavelength band to 629-630 nm and a 655 nm form was observed which was inactive on irradiation. This inhibition may be caused by serious alteration of the enzyme structure resulting in the trans-localisation of NADPH within the active site of POR. and K. Lenti, F. Fodor, B. Böddi.
Rights:
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17. Photoinhibition in chilling stressed wheat and maize

Creator:
Lidon, F. C., Loureiro, A. S., Vieira, D. E., Bilhó, E. A., Nobre, P., and Costa, R.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carotenoids, chlorophyll, cytochrome, b559, lipid peroxidation, photosystems 1 and 2 proteins, quinones, Triticum, xanthophyll cycle, and Zea
Language:
Multiple languages
Description:
At chilling stress, the contents of photosynthetic pigments decreased significantly in maize, but in wheat the contents of chlorophyll (Chl) remained unchanged whereas the contents of total carotenoids (Car) increased. In both species the contents of α+β carotene and lutein + lutein-5,6-epoxide remained unaffected, but the de-epoxidation state involving the components of the xanthophyll cycle increased. Under chilling stress the photosynthetic electron transport also displayed a general failure in maize but in wheat only photosystem (PS) 2 coupled to the water oxidation complex was inhibited. Moreover, in stressed maize the quinone pool decreased, while the low and high potential forms of cytochrome b559 increased. In wheat only the contents of cytochrome b559LP decreased. Peroxidation of acyl lipids in the chloroplast lamellae became more distinct in chilling stressed maize but could also be detected in wheat. Thus in chilling stressed maize prevails an impairment of the acceptor site of PS2 while in wheat photodamage is restricted to the electron donation pathway from water to P680 or to the oxygen evolving complex. and F. C. Lidon ... [et al.].
Rights:
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18. Photosynthetic acclimation to CO2 enrichment related to ribulose-1,5-bisphosphate carboxylation limitation in wheat

Creator:
Zhang, D.-Y., Chen, G.-Y., Chen, J., Yong, Z.-H., Zhu, J.-G., and Xu, D.-Q.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
maximum in vivo electron transport rate, net photosynthetic rate, ribulose-1,5-bisphosphate carboxylase, oxygenase activase, RuBP regeneration limitation, sucrose-phosphate synthase, and Triticum
Language:
Multiple languages
Description:
Net photosynthetic rate (PN) measured at the same CO2 concentration, the maximum in vivo carboxylation rate, and contents of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBPCO) and RuBPCO activase were significantly decreased, but the maximum in vivo electron transport rate and RuBP content had no significant change in CO2-enriched [EC, about 200 µmol mol-1 above the ambient CO2 concentration (AC)] wheat leaves compared with those in AC grown wheat leaves. Hence photosynthetic acclimation in wheat leaves to EC is largely due to RuBP carboxylation limitation. and D.-Y. Zhang ... [et al.].
Rights:
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19. Photosynthetic response of wheat and sunflower cultivars to long-term exposure of elevated carbon dioxide concentration

Creator:
Pandurangam, V., Sharma-Natu, P., Shreekanth, B., and Ghildiyal, M. C.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
cultivar differences, feedback inhibition, Helianthus, photosynthetic acclimation, species differences, starch, sugars, and Triticum
Language:
Multiple languages
Description:
Wheat (Triticum aestivum L. cv. HD 2329 and DL 1266-5) and sunflower (Helianthus annuus L. cv. MSFH 17 and MRSF 1754) plants were grown in field under atmospheric (360±10 cm3 m-3, AC) and elevated (650±50 cm3 m-3, EC) CO2 concentrations in open top chambers for entire period of growth and development till maturity. Net photosynthetic rate (P N) of wheat cvs. when compared at the same internal CO2 concentration (Ci), by generating PN/Ci curves, showed lower PN in EC plants than in AC ones. EC-grown wheat cultivars also showed a lesser response to irradiance than AC plants. In sunflower cultivars, PN/Ci curves and irradiance response curves were not significantly different in AC and EC plants. CO2 and irradiance responses of photosynthesis, therefore, further revealed a down-regulation of P N in wheat but not so in sunflower under long-term CO2 enrichment. Wheat cvs. accumulated in leaves mostly sugars, whereas sunflower accumulated mainly starch. This further strengthened the view that accumulation of excess assimilates in the leaves under EC as starch is not inhibitory to PN. and V. Pandurangam ... [et al.].
Rights:
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20. Plant photosynthetic production as controlled by leaf growth, phenology, and behavior

Creator:
Begonia, G. B. and Begonia, M. T.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Arabidopsis, cultivar differences, genetics, Glycine, leaf area index, Oryza, Pisum, Sorghum, and Triticum
Language:
Multiple languages
Description:
In this historical review we summarize discoveries related to the flowering genes in controlling leaf area index (LAI, the leaf area per unit ground area) in sorghum, soybean, or pea crop stands. We also analyze similar work on Arabidopsis and dwarf and intermediate stem height genes in wheat and rice. and G. B. Begonia, M. T. Begonia.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public