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1.
Howard Gest 《Photosynthesis research》1993,35(1):87-96
Experiments of Hans Molisch in 1907 demonstrated that purple bacteria do not evolve molecular oxygen during photosynthetic metabolism, and can use organic compounds as sources of cell carbon for anaerobic ‘photoheterotrophic’ growth. Molisch's conclusion that he discovered a new photosynthetic growth mode was not accepted for some 30 years because of the prevailing definition of photosynthesis as light-dependent conversion of carbon dioxide and inorganic reductants to cell materials. Meanwhile, during the decade of the 1930s, Cornelis van Niel formulated the ‘comparative biochemical watercleavage hypothesis’ of photosynthesis, which enjoyed great popularity for about 20 years. According to this concept, photolysis of water yielded ‘H’ and ‘OH’, the former acting as the hydrogen donor for CO2 reduction in all modes of photosynthesis. Oxygenic organisms were presumed to contain a unique biochemical system capable of converting ‘OH’ to water and O2. To explain the absence of O2 formation by purple and green photosynthetic bacteria, it was supposed that such organisms lacked the oxygen-forming system and, instead, ‘OH’ was disposed of by reduction with an inorganic H(e) donor (other than water) according to the general equation: $$2 'OH' + H_2 A \to 2 H_2 O + A ,$$ where H2A is H2 or an inorganic sulfur compound. Critical tests of van Niel's hypothesis could not be devised, and his proposal was abandoned soon after the discovery of in vitro photophosphorylation by green plant chloroplasts and membranes of purple bacteria in 1954. Photophosphorylation was then viewed as one key common denominator of oxygenic and anoxygenic photosyntheses. From later research it became clear that light-dependent phosphorylation of adenosine diphosphate was a consequence of photochemical charge separation and electron flow in reaction centers embedded in membranes of all photosynthetic organisms. The similarities, as well as the differences, in fine structure and function of reaction centers in anoxygenic and oxygenic organisms are now believed to reflect the course of evolution of oxygenic organisms from anoxygenic photosynthetic precursors. Thus, with the acquisition of new knowledge, concepts of the comparative biochemistry of photosynthetic processes have been radically altered during the past several decades. This paper describes highpoints of the history of these changes. 相似文献
2.
John M. Olson 《Bio Systems》1981,14(1):89-94
The common ancestor of all photosynthetic prokaryotes and organelles contained chlorophyll (Chl) a. All green and purple photosynthetic bacteria descended from a common bacteriochlorophyll (Bchl) a-containing ancestor which diverged from the Chl a line. Separate PS-I and PS-II reaction centers may have evolved before the appearance of Bchl a. When the transition to Bchl a occurred, the resultant organism contained two types of reaction center, “PS-I” and “PS-II.” One line of development eliminated “PS-II” and evolved into the green bacteria. The other line eliminated “PS-I” and became the purple bacteria. In the Chl a-containing organisms the evolution of PS-II continued until oxygen evolution was achieved. 相似文献
3.
Drews G 《Photosynthesis research》2005,83(1):25-34
Theodor Wilhelm Engelmann (1843–1909), who had a creative life in music, muscle physiology, and microbiology, developed a sensitive method for tracing the photosynthetic oxygen production of unicellular plants by means of bacterial aerotaxis (chemotaxis). He discovered the absorption spectrum of bacteriopurpurin (bacteriochlorophyll a) and the scotophobic response, photokinesis, and photosynthesis of purple bacteria. 相似文献
4.
Alfred Russell Wallace was a field naturalist with a strong interest in general physiology. In this vein, he wrote that oxygen (O2), produced by green plants, is “the food of protoplasm, without which it cannot continue to live”. Here we summarize current models relating body size to respiration rates (in the context of the metabolic scaling theory) and show that oxygen-uptake activities, measured at 21 vol.% O2, correlate closely with growth patterns at the level of specific organs within the same plant. Thus, whole plant respiration can change ontogenetically, corresponding to alterations in the volume fractions of different tissues. Then, we describe the evolution of cyanobacterial photosynthesis during the Paleoarchean, which changed the world forever. By slowly converting what was once a reducing atmosphere to an oxidizing one, microbes capable of O2-producing photosynthesis modified the chemical nature and distribution of the element iron (Fe), slowly drove some of the most ancient prokaryotes to extinction, created the ozone (O3) layer that subsequently shielded the first terrestrial plants and animals from harmful UV radiation, but also made it possible for Earth’s forest to burn, sometimes with catastrophic consequences. Yet another paradox is that the most abundant protein (i.e., the enzyme Rubisco, Ribulose-1,5-biphosphate carboxylase/oxygenase) has a greater affinity for oxygen than for carbon dioxide (CO2), even though its function is to bind with the latter rather than the former. We evaluate this second “oxygen paradox” within the context of photorespiratory carbon loss and crop yield reduction in C3 vs. C4 plants (rye vs. maize). Finally, we analyze the occurrence of reactive oxygen species (ROS) as destructive by-products of cellular metabolism, and discuss the three “O2-paradoxa” with reference to A. R. Wallace’s speculations on “design in nature”. 相似文献
5.
Ingrid Tichá 《Biologia Plantarum》1976,18(3):237-240
Plants ofPlectranthus fructicosus were grown in two controlled environments -“spring” and “summer” conditions - differing in temperature and air humidity (day/night 20/15 and 27/22 °C; 80/98 and 50/80 % relative humidity) in order to study the influence of environmental conditions on the development of photosynthetic characteristics of individual leaves. The contribution of individual leaves to plant photosynthesis was very similar in both environments, the maximum shifting from bottom leaves to leaves of middle insertion levels during plant ontogenesis. On integrating the values of leaf photosynthesis for the whole vegetation period, the 5th leaf in “spring” conditions and the 4th leaf in “summer” conditions showed the highest contribution to plant photosynthesis (29 % resp. 25% of total net CO2 influx). The “photosynthetically mature” leaves of middle insertion levels played the main role in CO2 uptake of whole plant. 相似文献
6.
Selection and characterization of tobacco plants with novel o(2)-resistant photosynthesis 总被引:2,自引:2,他引:0
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Zelitch I 《Plant physiology》1989,90(4):1457-1464
Plants were obtained with novel O2-resistant photosynthetic characteristics. At low CO2 (250-350 μL CO2 L−1) and 30°C when O2 was increased from 1% to 21% to 42%, the ratio of net CO2 uptake in O2-resistant whole plants or leaf discs compared to wild type increased progressively, and this was not related to stomatal opening. Dihaploid plantlets regenerated from anther culture were initially screened and selected for O2-resistant growth in 42% O2/160 μL CO2 L−1 and 0.18% of the plantlets showed O2-resistant photosynthesis. About 30% of the progeny (6 of 19 plants) of the first selfing of a fertile plant derived from a resistant dihaploid plant had O2-resistant photosynthesis, and after a second selfing this increased to 50% (6 of 12 plants). In 21% O2 and low CO2, net photosynthesis of the resistant plants was about 15% greater on a leaf area basis than wild type. Net photosynthesis was compared in leaf discs at 30 and 38°C in 21% O2, and at the higher temperature O2-resistant plants showed still greater photosynthesis than wild type. The results suggest that the O2-resistant photosynthesis described here is associated with a decreased stoichiometry of CO2 release under conditions of rapid photorespiration. This view was supported by the finding that leaves of O2-resistant plants averaged 40% greater catalase activity than wild type. 相似文献
7.
《BBA》2023,1864(3):148974
Photosynthetic conversion of light energy into chemical energy occurs in sheet-like membrane-bound compartments called thylakoids and is mediated by large integral membrane protein-pigment complexes called reaction centers (RCs). Oxygenic photosynthesis of higher plants, cyanobacteria and algae requires the symbiotic linking of two RCs, photosystem II (PSII) and photosystem I (PSI), to split water and assimilate carbon dioxide. Worldwide there is a large research investment in developing RC-based hybrids that utilize the highly evolved solar energy conversion capabilities of RCs to power catalytic reactions for solar fuel generation. Of particular interest is the solar-powered production of H2, a clean and renewable energy source that can replace carbon-based fossil fuels and help provide for ever-increasing global energy demands. Recently, we developed thylakoid membrane hybrids with abiotic catalysts and demonstrated that photosynthetic Z-scheme electron flow from the light-driven water oxidation at PSII can drive H2 production from PSI. One of these hybrid systems was created by self-assembling Pt-nanoparticles (PtNPs) with the stromal subunits of PSI that extend beyond the membrane plane in both spinach and cyanobacterial thylakoids. Using PtNPs as site-specific probe molecules, we report the electron microscopic (EM) imaging of oligomeric structure, location and organization of PSI in thylakoid membranes and provide the first direct visualization of photosynthetic Z-scheme solar water-splitting biohybrids for clean H2 production. 相似文献
8.
Phototrophic diazotrophs include the photosynthetic green and purple bacteria, the heliobacteria, many cyanobacteria and the unusual chlorophyll-containing rhizobia that are found in the stem nodules of Aeschynomene spp. In this review, which concentrates on cyanobacteria, the interrelations between photosynthesis and N2 fixation are discussed. Photosynthesis can, in theory, directly provide the ATP and reductant needed to support N2 fixation but the link between these two processes is usually indirect, mediated through accumulated carbon reserves. In cyanobacteria, which possess an oxygenic photosynthesis, this serves to separate the O2 that is produced by photosynthesis from the O2-sensitive nitrogenase. However, in certain circumstances, oxygenic photosynthesis and N2 fixation coexist. Under these conditions, respiratory consumption of photosynthetically generated O2 may have an important role in minimizing O2-damage to nitrogenase. 相似文献
9.
Temperature response of photosynthesis in C3, C4, and CAM plants: temperature acclimation and temperature adaptation 总被引:2,自引:0,他引:2
Most plants show considerable capacity to adjust their photosynthetic characteristics to their growth temperatures (temperature acclimation). The most typical case is a shift in the optimum temperature for photosynthesis, which can maximize the photosynthetic rate at the growth temperature. These plastic adjustments can allow plants to photosynthesize more efficiently at their new growth temperatures. In this review article, we summarize the basic differences in photosynthetic reactions in C3, C4, and CAM plants. We review the current understanding of the temperature responses of C3, C4, and CAM photosynthesis, and then discuss the underlying physiological and biochemical mechanisms for temperature acclimation of photosynthesis in each photosynthetic type. Finally, we use the published data to evaluate the extent of photosynthetic temperature acclimation in higher plants, and analyze which plant groups (i.e., photosynthetic types and functional types) have a greater inherent ability for photosynthetic acclimation to temperature than others, since there have been reported interspecific variations in this ability. We found that the inherent ability for temperature acclimation of photosynthesis was different: (1) among C3, C4, and CAM species; and (2) among functional types within C3 plants. C3 plants generally had a greater ability for temperature acclimation of photosynthesis across a broad temperature range, CAM plants acclimated day and night photosynthetic process differentially to temperature, and C4 plants was adapted to warm environments. Moreover, within C3 species, evergreen woody plants and perennial herbaceous plants showed greater temperature homeostasis of photosynthesis (i.e., the photosynthetic rate at high-growth temperature divided by that at low-growth temperature was close to 1.0) than deciduous woody plants and annual herbaceous plants, indicating that photosynthetic acclimation would be particularly important in perennial, long-lived species that would experience a rise in growing season temperatures over their lifespan. Interestingly, across growth temperatures, the extent of temperature homeostasis of photosynthesis was maintained irrespective of the extent of the change in the optimum temperature for photosynthesis (T opt), indicating that some plants achieve greater photosynthesis at the growth temperature by shifting T opt, whereas others can also achieve greater photosynthesis at the growth temperature by changing the shape of the photosynthesis–temperature curve without shifting T opt. It is considered that these differences in the inherent stability of temperature acclimation of photosynthesis would be reflected by differences in the limiting steps of photosynthetic rate. 相似文献
10.
Discovery and characterization of electron transfer proteins in the photosynthetic bacteria 总被引:4,自引:0,他引:4
Research on photosynthetic electron transfer closely parallels that of other electron transfer pathways and in many cases
they overlap. Thus, the first bacterial cytochrome to be characterized, called cytochrome c
2, is commonly found in non-sulfur purple photosynthetic bacteria and is a close homolog of mitochondrial cytochrome c. The cytochrome bc
1 complex is an integral part of photosynthetic electron transfer yet, like cytochrome c
2, was first recognized as a respiratory component. Cytochromes c
2 mediate electron transfer between the cytochrome bc
1 complex and photosynthetic reaction centers and cytochrome a-type oxidases. Not all photosynthetic bacteria contain cytochrome c
2; instead it is thought that HiPIP, auracyanin, Halorhodospira cytochrome c551, Chlorobium cytochrome c555, and cytochrome c
8 may function in a similar manner as photosynthetic electron carriers between the cytochrome bc
1 complex and reaction centers. More often than not, the soluble or periplasmic mediators do not interact directly with the
reaction center bacteriochlorophyll, but require the presence of membrane-bound intermediates: a tetraheme cytochrome c in purple bacteria and a monoheme cytochrome c in green bacteria. Cyclic electron transfer in photosynthesis requires that the redox potential of the system be delicately
poised for optimum efficiency. In fact, lack of redox poise may be one of the defects in the aerobic phototrophic bacteria.
Thus, large concentrations of cytochromes c
2 and c′ may additionally poise the redox potential of the cyclic photosystem of purple bacteria. Other cytochromes, such as flavocytochrome
c (FCSD or SoxEF) and cytochrome c551 (SoxA), may feed electrons from sulfide, sulfur, and thiosulfate into the photosynthetic pathways via the same soluble
carriers as are part of the cyclic system.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
11.
Max M. Tilzer Anna Hillbricht-Ilkowska Andrzej Kowalczewski Irena Spodniewska Joanna Turczyska 《International Review of Hydrobiology》1977,62(2):279-289
Photosynthetic rates as measured by the oxygen light and dark bottle method were highly correlated with estimates using the 14C technique. The high O2/14C ratios found are explained by algal respiration and extracellular release which are included in photosynthetic measurements by the oxygen technique, while the 14C method yields values close to net photosynthesis. Separation of net- and nannoplankton using a 50 μm plankton net for filtration was not comparable to distinctions made by microscopic examination. Separation of both by filtration caused a significant decrease in the photosynthetic activity of nannoplankton in 24-hour incubations, but had no detectable effect after 4 hours of exposure. “Bottle effects” in 24-hour measurements of photosynthesis were similar using both methods. Asymmetric photosynthetic time-curves as well as vertical phytoplankton migrations were the main reasons for errors in estimates of daily photosynthetic rates from part-day incubations which were extrapolated to the entire day. 相似文献
12.
Developmental Changes in Photosynthetic Gas Exchange in the Polyol-Synthesizing Species, Apium graveolens L. (Celery) 总被引:6,自引:5,他引:1
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Developmental changes in photosynthetic gas exchange were investigated in the mannitol synthesizing plant celery (Apium graveolens L. `Giant Pascal'). Greenhouse-grown plants had unusually high photosynthetic rates for a C3 plant, but consistent with field productivity data reported elsewhere for this plant. In most respects, celery exhibited typical C3 photosynthetic characteristics; light saturation occurred at 600 micromoles photons per square meter per second, with a broad temperature optimum, peaking at 26°C. At 2% O2, photosynthesis was enhanced 15 to 25% compared to rates at 21% O2. However, celery had low CO2 compensation points, averaging 7 to 20 microliters per liter throughout the canopy. Conventional mechanisms for concentrating CO2 were not detectable. 相似文献
13.
A. A. Thwe G. Vercambre H. Gautier F. Gay J. Phattaralerphong P. Kasemsap 《Photosynthetica》2014,52(1):105-116
The crop sensitivity to ozone (O3) is affected by the timing of the O3 exposure, by the O3 concentration, and by the crop age. To determine the physiological response to the acute ozone stress, tomato plants were exposed to O3 at two growth stages. In Experiment I (Exp. I), O3 (500 μg m?3) was applied to 30-d-old plants (PL30). In Experiment II (Exp. II), three O3 concentrations (200, 350, and 500 μg m?3) were applied to 51-d-old plants (PL51). The time of the treatment was 4 h (7:30–11:30 h). Photosynthesis and chlorophyll fluorescence measurements were done 4 times (before the exposure; 20 min, 20 h, and 2–3 weeks after the end of the treatment) using a LI-COR 6400 photosynthesis meter. The stomatal pore area and stomatal conductance were reduced as the O3 concentration increased. Ozone induced the decrease in the photosynthetic parameters of tomato regardless of the plant age. Both the photosystem (PS) II operating efficiency and the maximum quantum efficiency of PSII photochemistry declined under the ozone stress suggesting that the PSII activity was inhibited by O3. The impaired PSII contributed to the reduced photosynthetic rate. The greater decline of photosynthetic parameters was found in the PL30 compared with the PL51. It proved the age-dependent ozone sensitivity of tomato, where the younger plants were more vulnerable. Ozone caused the degradation of photosynthetic apparatus, which affected the photosynthesis of tomato plants depending on the growth stage and the O3 concentration. 相似文献
14.
The influence of environmental factors on apparent photosynthesis and respiration of the submersed macrophyte Elodea canadensis 总被引:3,自引:3,他引:0
Abstract Oxygen effects on apparent photosynthetic and dark respiratory O2 exchange rates of detached leaves of Elodea canadensis Michx. (Hydrocharitaceae) were determined over a range of conditions which the submersed plant is likely to experience in shallow water. Apparent photosynthesis is inhibited by O2 under all the experimental regimes of light, temperature, CO2 concentration and pH. This inhibition is not caused solely by an accelerated rate of dark respiration, and the observed variations in O2 inhibition are comparable to O2 effects on photosynthesis and photorespiration of terrestrial C3 plants. Percentage inhibition of apparent photosynthesis is enhanced by high O2 and also by low CO2. These results indicate that high O2, high pH and low CO2 conditions could cause major losses in photosynthetic activity under field conditions. This may account for some of the losses in biomass that are observed under still water conditions. 相似文献
15.
Modification of Carbon Partitioning, Photosynthetic Capacity, and
O2 Sensitivity in Arabidopsis Plants with Low
ADP-Glucose Pyrophosphorylase Activity
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Wild-type Arabidopsis plants, the starch-deficient mutant TL46, and the near-starchless mutant TL25 were evaluated by noninvasive in situ methods for their capacity for net CO2 assimilation, true rates of photosynthetic O2 evolution (determined from chlorophyll fluorescence measurements of photosystem II), partitioning of photosynthate into sucrose and starch, and plant growth. Compared with wild-type plants, the starch mutants showed reduced photosynthetic capacity, with the largest reduction occurring in mutant TL25 subjected to high light and increased CO2 partial pressure. The extent of stimulation of CO2 assimilation by increasing CO2 or by reducing O2 partial pressure was significantly less for the starch mutants than for wild-type plants. Under high light and moderate to high levels of CO2, the rates of CO2 assimilation and O2 evolution and the percentage inhibition of photosynthesis by low O2 were higher for the wild type than for the mutants. The relative rates of 14CO2 incorporation into starch under high light and high CO2 followed the patterns of photosynthetic capacity, with TL46 showing 31% to 40% of the starch-labeling rates of the wild type and TL25 showing less than 14% incorporation. Overall, there were significant correlations between the rates of starch synthesis and CO2 assimilation and between the rates of starch synthesis and cumulative leaf area. These results indicate that leaf starch plays an important role as a transient reserve, the synthesis of which can ameliorate any potential reduction in photosynthesis caused by feedback regulation. 相似文献
16.
Despite the evidence for a critical role of Mn in malate decarboxylation and CO2 release for carbon fixation reactions in C-4 plants, there is a lack of information on their Mn requirement. The objective of this study was to establish Mn levels needed for optimum growth and photosynthesis of four agriculturally important C-4 species, NAD-ME C-4 pearl millet and purple amaranth, and NADP-ME C-4 corn and sorghum, as compared to two C-3 species, wheat and squash. Plants were grown hydroponically in a complete nutrient solution with Mn concentrations ranging from 0 to 100 μM. We report that under these conditions, C-3 and NADP-ME C-4 plants reached their maximum biomass production with 2–5 μM Mn, the concentration commonly used in plant nutrient media. In contrast, Mn concentrations supporting maximum performance of NAD-ME C-4 plants were up to 20-fold higher and ranged between 50 and 100 μM. Although leaf tissue Mn concentrations increased in parallel with Mn nutrition in all plants, the higher leaf Mn had no effect on NADP-ME C-4 or C-3 plants, but it caused a large, up to 100%, increase in net photosynthetic rate in NAD-ME C-4 species. The highest photosynthetic rates across the spectrum of photon flux density were recorded for C-3 and NADP-ME C-4 plants receiving 2–5 μM Mn, and for NAD-ME C-4 species millet and amaranth supplied with 50 or 100 μM Mn, respectively. Squash (C-3) plants were the most sensitive to Mn and their photosynthetic rate was severely depressed with more than 10 μM Mn. The increase in photosynthetic rates of NAD-ME C-4 species occurred without an increase in stomatal conductance, eliminating CO2 uptake as the main cause. We propose that the higher photosynthetic rates in NAD-ME C-4 species supplied with higher Mn were a result of increased activation of the Mn-dependent NAD-ME in bundle sheath cells, producing greater CO2 supply for Calvin cycle reactions. This is, to our knowledge, the first report on a significantly higher Mn requirement for optimum photosynthesis and biomass production of NAD-ME C-4 species. 相似文献
17.
Katsumi Matsuura 《Journal of plant research》1994,107(2):191-200
The cyclic electron transfer system in purple bacteria is composed of the photosynthetic reaction center, the cytochromebc
1 complex, cytochromec
2, and ubiquinone. These components share many characteristics with those of photosynthesis and respiration in other organisms.
Studies of the cyclic electron transfer system have provided useful insights about the evolution and general mechanisms of
membranous energy-conserving systems. The photosynthetic system in purple bacteria may represent a prototype of highly efficient,
energy-conserving electron transfer systems in the organisms.
Recipient of the Botanical Society Award of Young Scientists, 1992 相似文献
18.
We addressed the question: “Are short-term, leaf-level measurements of photosynthesis correlated with long-term patterns of plant success?” in a productive grassland where interspecific competitive interactions are important. To answer this question, seasonal patterns of leaf-level photosynthesis were measured in 27 tallgrass prairie species growing in sites that differed in species composition and productivity due to differences in fire history. Our specific goals were to assess the relationship between gas exchange under field conditions and success (defined as aerial plant cover) for a wide range of species, as well as for these species grouped as dominant and sub-dominant grasses, forbs, and woody plants. Because fire increases productivity and dominance by grasses in this system, we hypothesized that any relationship between photosynthesis and success would be strongest in annually burned sites. We also predicted that regardless of fire history, the dominant species (primarily C4 grasses) would have higher photosynthetic rates than the less successful species (primarily C3 grasses, forbs and woody plants). Because forbs and woody species are less abundant in annually burned sites, we expected that these species would have lower photosynthetic rates in annually burned than in infrequently burned sites. As expected, the dominant C4?grasses had the highest cover on all sites, relative to?other growth forms, and they had the highest maximum and seasonally averaged photosynthetic rates (17.6 ± 0.42 μmol m?2 s?1). Woody species had the lowest average cover as well as the lowest average photosynthetic rates, with subdominant grasses and forbs intermediate in both cover and photosynthesis. Also as predicted, the highest overall photosynthetic rates were found on the most productive annually burned site. Perhaps most importantly, a positive relationship was found between leaf-level photosynthesis and cover for a core group of species when data were combined across all sites. These data support the hypothesis that higher instantaneous rates of leaf-level photosynthesis are indicative of long-term plant success in this grassland. However, in contrast to our predictions, the subdominant grasses, forbs and woody species on the annually burned site had higher photosynthetic rates than in the less frequently burned sites, even though their average cover was lower on annually burned sites, and hence they were less successful. The direct negative effect of fire on plant cover and species-specific differences in the availability of resources may explain why photosynthesis was high but cover was low in some growth forms in annually burned sites. 相似文献
19.
We investigated the influence of exogenously sourced ethylene (200 μL L?1 ethephon) in the protection of photosynthesis against 200 mg kg?1 soil each of nickel (Ni)- and zinc (Zn)-accrued stress in mustard (Brassica juncea L.). Plants grown with Ni or Zn but without ethephon exhibited increased activity of 1-aminocyclopropane carboxylic acid synthase, and ethylene with increased oxidative stress measured as H2O2 content and lipid peroxidation compared with control plants. The oxidative stress in Ni-grown plants was higher than Zn-grown plants. Under metal stress, ethylene protected photosynthetic potential by efficient PS II activity and through increased activity of ribulose-1,5-bisphosphate carboxylase and photosynthetic nitrogen use efficiency (P-NUE). Application of 200 μL L?1 ethephon to Ni- or Zn-grown plants significantly alleviated toxicity and reduced the oxidative stress to a greater extent together with the improved net photosynthesis due to induced activity of ascorbate peroxidase and glutathione (GSH) reductase, resulting in increased production of reduced GSH. Ethylene formation resulting from ethephon application alleviated Ni and Zn stress by reducing oxidative stress caused by stress ethylene production and maintained increased GSH pool. The involvement of ethylene in reversal of photosynthetic inhibition by Ni and Zn stress was related to the changes in PS II activity, P-NUE, and antioxidant capacity was confirmed using ethylene action inhibitor, norbornadiene. 相似文献
20.
Howard Gest 《Photosynthesis research》1991,30(1):49-59
Hans Molisch (1856–1937) was an exceptionally gifted and productive researcher who had broad interests in plant biology, physiology and biochemistry. In addition, he pioneered in isolating a number of species of purple photosynthetic bacteria in pure culture (including Rhodobacter capsulatus), which facilitated his discovery of basic aspects of bacterial photosynthesis. Molisch demonstrated conclusively that molecular oxygen is not produced by photosynthetic bacteria, and discovered the photoheterotrophic growth mode. The range of Molisch's research accomplishments was impressive, and he emerges as a major figure in the history of photosynthesis research. This essay reviews the numerous research contributions made by Molisch, particularly in regard to advancing knowledge of the several forms of photosynthetic metabolism. An English translation of his 1914 paper on the photosynthetic creation of visual images on leaves is included as an Appendix. 相似文献