Effect of copper on cellular processes in higher plants

W. Maksymiec

Photosynthetica 1996, 34(3):321-342 | DOI: 10.1023/A:1006818815528

Copper (Cu) is a heavy metal which in recent studies has been attributed an increasing role in metabolic processes of plant cells. It is an indispensable component of oxidative enzymes or of particular structural components of cells. At elevated concentrations, Cu can act strongly on chromatin, the photosynthetic apparatus, growth, and senescence processes. The mechanisms of the metal toxicity depending largely on the growth stage of treated plants are presented in this review.

Mechanisms of non-photochemical chlorophyll fluorescence quenching in higher plants

P. Pospíšil

Photosynthetica 1996, 34(3):343-355 | DOI: 10.1023/A:1006803832366

The excitation energy of pigment molecules in photosynthetic antennae systems is utilised by photochemistry, partly it is thermally dissipated, and partly it is emitted as fluorescence. Changes in the quantum yield of chlorophyll (Chl) fluorescence reflect the changes in quantum yield of photochemical reaction and thermal dissipation of the excitation energy. Decrease of the Chl fluorescence quantum yield is called the Chl fluorescence quenching. The decrease of the quantum yield that is accompanied by photochemical reactions has been termed the photochemical quenching, and the decrease accompanied by thermal dissipation of the excitation energy is...

Day, R.A.: Scientific English. A Guide for Scientists and Other Professionals

Z. Šesták

Photosynthetica 1996, 34(3):356 | DOI: 10.1023/A:1006884622797

Physiological significance of proline and glycinebetaine: Maintaining photosynthesis during NaCl stress in wheat

L.R. Rajasekaran, P.E. Kriedemann, D. Aspinall, L.G. Paleg

Photosynthetica 1996, 34(3):357-366 | DOI: 10.1023/A:1006855816437

Experiments on the physiological significance of accumulation of proline and glycinebetaine (GB) in sustaining photosynthesis during salt stress in wheat in vivo showed that pre-treatment with GB, but not proline, alleviated NaCl-induced stomatal and non-stomatal inhibition of photosynthesis completely. A permeating and non-dissociating osmoticum, 3-orthomethyl-glucopyranose, also alleviated NaCl-induced perturbations of photosynthesis, suggesting that GB may work by maintaining chloroplast volume and not by specific effects on photosynthetic processes.

Photosynthetic utilization of radiant energy by CAM Dendrobium flowers

G.H. Khoo, J. He, C.S. Hew

Photosynthetica 1996, 34(3):367-376 | DOI: 10.1023/A:1006807900507

14CO2 fixation was observed in orchid Dendrobium flowers; its rate decreased with the flower development. Chlorophyll (Chl) fluorescence in different developmental stages of flowers was compared to other green plant parts (leaf, inflorescence stalk, and fruit capsule). The photochemical efficiency of photosystem 2 (PS2) (Fv/Fm) of a leaf was 14-21 % higher than that of a mature flower perianth (sepal, petal, and labellum) which had a much lower total Chl content and Chl a/b ratio. A higher quantum yield of PS2 (ΦPS2) than in the mature flowers was observed in all green parts. Flower sepals had higher Chl content, Chl a/b ratio, and Fv/Fm values...

Changes in French bean cotyledon composition associated with modulated life-span

N. Wilhelmová, J. Wilhelm, J. Kutík, D. Haisel

Photosynthetica 1996, 34(3):377-391 | DOI: 10.1023/A:1006859917345

The onset of Phaseolus vulgaris L. cotyledon senescence and its characteristics were modulated by irradiance (higher or lower than standard) and by epicotyl decapitation. The cotyledon life-span of 16 d was not influenced by irradiance while decapitation prolonged the life-span to 28 d. The fresh mass of cotyledons, an indicator of organ viability, decreased in a similar manner in all non-decapitated plants, though it was relatively slower in plants grown under a low irradiance (LI). Three days after decapitation the fresh mass of cotyledons increased by one third, a slight decrease was observed on the 21st d, and it lasted until the end of the life...

Aluminium modulation of the photosynthetic carbon reduction cycle in Zea mays

F.C. Lidon, J.C. Ramalho, M.G. Barreiro

Photosynthetica 1996, 34(3):393-400 | DOI: 10.1023/A:1006812118254

Two-weeks-old maize (Zea mays L. cv. XL-72.3) plants were submitted to Al concentrations of 0-81 g m-3 for 20 d, after which the A1 concentration-dependent effects on CO2 uptake by the mesophyll tissue and subsequent CO2 assimilation in the photosynthetic carbon reduction cycle of bundle sheath cells were investigated. The net photosynthetic rate (PN) and stomatal conductance (gs) increased continuously up to 27 g m-3 Al, whereas the intercellular CO2 concentration showed minimum values with the 27 g m-3 Al treatment. Moreover, the starch and saccharide concentrations, and fructose-1,6-bisphosphatase did not change significantly with increasing Al...

Influence of supplemental UV-B radiation on photosynthetic characteristics of rice plants

Navin Kumar Ambasht, Madhoolika Agrawal

Photosynthetica 1996, 34(3):401-408 | DOI: 10.1023/A:1006816202324

In a field experiment with rice (Oryza sativa L. cv. Saket 4) grown under ambient and supplemental ultraviolet-B (UV-B) radiation at 20 % ozone depletion, differences in gas exchange, concentrations of photosynthetic pigments, anthocyanins and flavonoids, biomass accumulation, catalase and peroxidase activities, and contents of ascorbic acid and phenol were determined. Decline in photosynthesis was associated with reductions in stomatal conductance and concentrations of photosynthetic pigments. Enhanced UV-B radiation (eUV-B) increased the contents of flavonoid and phenolic compounds in leaves. Peroxidase activity increased and catalase activity was...

Leaf gas exchange of cassava as affected by quality of planting material and water stress

M.G. Cayón, M.A. El-Sharkawy, L.F. Cadavid

Photosynthetica 1996, 34(3):409-418 | DOI: 10.1023/A:1006868219162

Field trial was conducted to study the effects of quality of planting material and prolonged water stress on leaf gas exchange of the cassava (Manihot esculenta Crantz) cultivar M Col 1684. Nutrient contents of planting material affected rootlet formation, but not leaf gas exchange. Net photosynthetic rate (PN), stomatal conductance (gs), and intercellular CO2 concentration (Ci) were significantly reduced by prolonged water stress. New leaves developed after recovery from water stress showed higher PN and gs, as compared to leaves of similar ages of unstressed plants. The higher PN was associated with higher leaf nutrient contents, indicating that...

Carbon allocation and partitioning in Vigna radiata (L.) Wilczek as affected by additional carbon gain

Aruna Sharma, U.K. Sengupta

Photosynthetica 1996, 34(3):419-426 | DOI: 10.1023/A:1006820303233

Carbon allocation to the source leaf, export and partitioning to the sink were studied in mungbean supplied by additional carbon from the source leaves subjected to high CO2 concentrations (600 and 900 cm3 m-3) in three metabolic and functional source-sink combinations. The plants were pruned to a source-path-sink system. With CO2 enrichment there was an appreciable increase in net photosynthetic CO2 uptake in earlier formed and physiologically younger leaves. Most of the carbon fixed as a result of enrichment was translocated out of the source leaf within one diurnal cycle. The carbon remaining in the source leaf was unchanged. Partitioning of extra...

Comparison of chlorophyll fluorescence kinetics and photochemical activities of isolated chloroplasts in genetic analysis of Lycopersicon esculentum Mill. hybrids

H. Synková, N. Wilhelmová, D. Holá, D. Haisel, Z. Šesták

Photosynthetica 1996, 34(3):427-438 | DOI: 10.1023/A:1006872320071

In experiments with 5x5 diallel cross of tomato cv. Smržické contents of individual chlorophylls (Chl) and carotenoids (Car), Chl fluorescence kinetic parameters (Fv/Fm, qp, qN and ΦII), activities of photosystem 2 and of the whole electron transport chain (Hill reaction) were compared during plant ontogeny with the aim to detect genetically determined differences among genotypes. The differences in Chl fluorescence kinetic parameters and Hill reaction activities were more affected by leaf development than by plant genotype, although the differences between reciprocal crosses were found in the former ones. Some additive genetic effects may participate...

Photoinhibition and recovery of photosynthesis in Coffea arabica and C. canephora

F.M. Da Matta, M. Maestri

Photosynthetica 1996, 34(3):439-446 | DOI: 10.1023/A:1006824404141

Photosynthetic parameters were determined in disks from leaves of C. arabica cv. Red Catuaí and C. canephora cv. Kouillou grown in the field. Kouillou showed a relatively higher irradiance requirement for saturating photosynthesis, lower chlorophyll (Chl) content, and higher Chl a/b ratio than Catuaí. Photoinhibition of photosynthesis under bright irradiance was manifested by decreases in maximum photochemical efficiency (evaluated by the variable to maximum fluorescence ratio, Fv/Fm), as a consequence of an increased initial and a quenched maximum fluorescence. Restoration of Fv/Fm following photoinhibition in low irradiance was faster in Kouillou...

Flow cytometric characteristics of subchloroplast particles prepared by the action of various detergents

N. Wilhelmová, S. Vaněk, J. Wilhelm

Photosynthetica 1996, 34(3):447-464 | DOI: 10.1023/A:1006876420980

Agranal thylakoid membranes from leaves of Phaseolus vulgaris L. were fragmented using seven distinct detergents: digitonin, Triton X-100, cetylpyridinium chloride, sodium dodecylsulfate, and Zwittergents 3-12, 3-14, and 3-16, differing in chemical composition and/or electric charges. Subchloroplast particles separated on a Percoll gradient were examined by flow cytometry to determine their size and shape. Vesicle size was also determined by a haematological analyzer, which produced comparable results. Individual green bands consisted of vesicles of fairly wide size distribution. Simple direct proportionality between the particle density and their...

Influence of ultraviolet-B radiation on photosynthetic and biochemical characteristics of a mangrove Rhizophora apiculata

P. Moorthy, K. Kathiresan

Photosynthetica 1996, 34(3):465-471 | DOI: 10.1023/A:1006828505050

Changes in photosynthesis and biochemical constituents were studied in R. apiculata seedlings grown under solar and solar enhanced UV-B radiation, equivalent to 10, 20, 30, and 40 % stratospheric ozone depletion. The seedlings grown under 10 % UV-B radiation showed an increase of 45 % net photosynthetic rate (PN) and 47 % stomatal conductance, while seedlings grown under 40 % UV-B radiation exhibited a decrease of 59 % PN with simultaneous elevation of 73 % intercellular CO2 concentration. Effects of UV-B on contents of lipids, saccharides, amino acids, and proteins were significant only at high doses of UV-B radiation. The concentration of anthocyanin...

Stomatal limitation of photosynthesis as affected by water stress and CO2 concentration

J. Janáček

Photosynthetica 1996, 34(3):473-476 | DOI: 10.1023/A:1006880521888

A water stress effect on photosynthesis and transpiration of wheat seedlings at 50-500 µmol(CO2) mol-1 was measured in an open gas exchange system. The limitation of photosynthesis by stomatal conductance was quantified by a stomatal control coefficient of the net photosynthetic rate. The stomatal control coefficient increased linearly as the water potential of root media decreased to -1 MPa, and it decreased with increasing CO2 concentration.

Chlorophyll fluorescence temperature curves of spruce needles from different whorls of the tree

P. Ilík, M. Vystrčilová, J. Nauš, J. Kalina

Photosynthetica 1996, 34(3):477-480 | DOI: 10.1023/A:1006832605959

The fluorescence temperature curves of one year old needles from upper whorls of spruce tree had an expressively higher high-temperature fluorescence peak (above 60 °C) than the needles from bottom whorls. These whorles were less irradiated and their needles had a lower chlorophyll a/b ratio than those from the upper whorls.