共查询到20条相似文献,搜索用时 31 毫秒
1.
When Porphyridium cruentum cells were illuminated with high fluence rate between 1900 and 4800 mol photons m-2s-1, a decrease in the photosynthetic activity of the cells was observed. Within the time frame of 20 min, and under the fluence rates studied, the sum of photons to be absorbed by cells (mg of chlorophyll (Chl), sufficient to initiate photoinhibition was calculated to be 9235.8 mol. The minimal specific light absorption rate to initiate photoinhibition in P. cruentum ranges between 2.29 and 4.26 mol photons s-1 mg-1 chl.a. There was a linear relationship between the specific rate of photoinhibition and the specific light absorption rate. A photon number of 2.56×104 mol mg-1 chl.a photoinhibited photosynthesis instantaneously. At 15°C, no photoinhibitory effect was observed at 2300 mol photons m-2 s-1 even after 45 min of illumination. At the other extreme of 35°C, 84% inhibition of photosynthetic activity was observed within 10 min of exposure to 2300 mol photons m-2 s-1. Between 20 and 30°C, the photoinhibitory effect was comparable. Photoinhibited P. cruentum cells recovered readily when transferred to low light (90 mol photons m-2 s-1) and darkness, and the specific rate of recovery was independent of the light intensity to which the cells were exposed, during the photoinhibitory treatment.Abbreviations Chlorophyll
QL, specific light absorption rate
Publication No. 28 of the Microalgal Biotechnology Laboratory 相似文献
2.
Carvalho Luisa C. Leonor Osório M. Manuela Chaves M. Amâncio Sara 《Plant Cell, Tissue and Organ Culture》2001,67(3):271-280
This study reports the effects of light availability during the acclimatization phase on photosynthetic characteristics of micropropagated plantlets of grapevine (Vitis vinifera L.) and of a chestnut hybrid (Castanea sativa × C. crenata). The plantlets were acclimatized for 4 weeks (grapevine) or 6 weeks (chestnut), under two irradiance treatments, 150 and 300 mol m–2 s–1 after in vitro phases at 50 mol m–2 s–1. For both treatments and both species, leaves formed during acclimatization (so-called `new leaves') showed higher photosynthetic capacity than the leaves formed in vitro either under heterotrophic or during acclimatization (so-called `persistent leaves'), although lower than leaves of young potted plants (so-called `greenhouse leaves'). In grapevine, unlike chestnut, net photosynthesis and biomass production increased significantly with increased light availability. Several parameters associated with chlorophyll a fluorescence indicated photoinhibition symptoms in chestnut leaves growing at 300 mol m–2 s–1. The results taken as a whole suggest that 300 mol m–2 s–1 is the upper threshold for acclimatization of chestnut although grapevine showed a better response than chestnut to an increase in light. 相似文献
3.
The light-dependent modulation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity was studied in two species: Phaseolus vulgaris L., which has high levels of the inhibitor of Rubisco activity, carboxyarabinitol 1-phosphate (CA1P), in the dark, and Chenopodium album L., which has little CA1P. In both species, the ratio of initial to fully-activated Rubisco activity declined by 40–50% within 60 min of a reduction in light from high a photosynthetic photon flux density (PPFD; >700 mol · m–2 · s–1) to a low PPFD (65 ± 15 mol · m–2 · s–1) or to darkness, indicating that decarbamylation of Rubisco is substantially involved in the initial regulatory response of Rubisco to a reduction in PPFD, even in species with potentially extensive CA1P inhibition. Total Rubisco activity was unaffected by PPFD in C. album, and prolonged exposure (2–6 h) to low light or darkness was accompanied by a slow decline in the activity ratio of this species. This indicates that the carbamylation state of Rubisco from C. album gradually declines for hours after the large initial drop in the first 60 min following light reduction. In P. vulgaris, the total activity of Rubisco declined by 10–30% within 1 h after a reduction in PPFD to below 100 mol · m–2 · s–1, indicating CA1P-binding contributes significantly to the reduction of Rubisco capacity during this period, but to a lesser extent than decarbamylation. With continued exposure of P. vulgaris leaves to very low PPFDs (< 30 mol · m–2 · s–1), the total activity of Rubisco declined steadily so that after 6–6.5 h of exposure to very low light or darkness, it was only 10–20% of the high-light value. These results indicate that while decarbamylation is more prominent in the initial regulatory response of Rubisco to a reduction in PPFD in P. vulgaris, binding of CA1P increases over time and after a few hours dominates the regulation of Rubisco activity in darkness and at very low PPFDs.Abbreviations CA1P
2-carboxyarabinitol 1-phosphate
- CABP
2-carboxyarabinitol 1,5-bisphosphate
- kcat
substrate-saturated turnover rate of fully carbamylated enzyme
- PPFD
photosynthetically active photon flux density (400–700 nm)
- Rubisco
ribulose-1,5-bisphosphate carboxylase/oxygenase
- RuBP
ribulose-1,5-bisphosphate 相似文献
4.
The increase in growth, determined by dry weight gain, of rice (Oryza sativa L.) and maize (Zea mays L.) caused by foliar applications of 9--L(+) adenosine, a putative second messenger elicited by triacontanol, was studied under different environmental conditions. Maize seedlings cultured in the greenhouse under approximately 100 mol m–2s–1 of light prior to treatment with L(+) adenosine did not respond unless they received supplemental light (250–300 mol m–2s–1) after treatment. Exposure of rice seedlings growing for 16 h at 150 mol m–2s–1 to short periods of 450 mol m–2s–1 (< than 20 min) had no effect on the positive response of rice to L(+) adenosine; however, exposure for 60 min or more increased the growth of rice and obviated the effect of L(+) adenosine. Rice seedlings treated with L(+) adenosine at different times during the day responded only when treated 9 to 12h after initiation of the photoperiod. Normal growing temperatures under different light intensities had little or no direct effect on the response of plants to L(+) adenosine. 相似文献
5.
Measurement of the light response of photosynthetic CO2 uptake is often used as an implement in ecophysiological studies. A method is described to calculate photosynthetic parameters, such as the maximum rate of whole electron transport and dissimilative respiration in the light, from the light response of CO2 uptake. Examples of the light-response curves of flag leaves and ears of wheat (Triticum aestivum cv. ARKAS) are shown.Abbreviations and symbols A
net photosynthesis rate
-
D
1
rate of dissimilative respiration occurring in the light
-
f
loss factor
-
I
incident PPFD
-
I
effective absorbed PPFD
-
J
rate of whole electron transport
-
J
m
maximum rate of whole electron transport
-
p
c
intercellular CO2 partial pressure
- PPFD
photosynthetic photon flux density
-
q
effectivity factor for the use of light (electrons/quanta)
-
absorption coefficient
-
I
*
CO2 compensation point in the absence of dissimilative respiration (bar)
-
II
conversion factor for calculation of CO2 uptake from the rate of whole electron transport
-
convexity factor
Gas-exchange rates relate to the projective area and are given in mol·m-2·s-1. Electron-transport rates are given in mol electrons·m-2·s-1; PPFD is given in mol quanta·m-2·s-1. 相似文献
6.
Moritoshi Iino 《Planta》1982,156(1):21-32
Brief irradiation of intact etiolated seedlings of maize (Zea mays L.) with red light (R; 30 W cm-2, 10 min) reduces the amounts of diffusible and free (solvent-extractable) indole-3-acetic acid (IAA) obtainable from excised coleoptile tips. The effect is transient, the lowest level (30% of the dark control) occurring at about 3 h after irradiation. The free-IAA content of the whole coleoptile and the diffusible-IAA yield from the base of the same organ are similarly reduced, whereas the conjugated-IAA content of the coleoptile is not affected. These results support the view that R inhibits the production of IAA at the coleoptile tip. It is further shown that R inhibits biosynthesis of [3H]IAA from [3H]tryptophan supplied to the coleoptile tip. The shapes of the fluence-response curves obtained for the reduction of the diffusible-IAA yield by R and far-red light (FR) indicate the participation of two photoreactive systems. One has thresholds at 10-3 W s cm2 of R, five orders of magnitude less than the minimum required for the appearance of spectrophotometrically measurable far-red-absorbing form of phytochrome (Pfr) in vivo, and 10-1 W s cm-2 of FR; its response is linear to the logarithm of fluence exceeding five orders of magnitude. The other system is seen above 102 W s cm-2 as an increase in the slope of the fluenceresponse curve; its response is FR reversible and related to the Pfr level of total photoreversible phytochrome. Both systems inhibit biosynthesis of IAA from tryptophan. Elongation of the coleoptile is stimulated by R; the stimulation is most apparent in the apical region, and is saturated with a fluence at which bo detectable pfr is formed. Farred light can also saturate this response. Since the endogenous IAA concentration in the coleoptile appears not to be in the inhibitory range, it is concluded that the stimulation of coleoptile elongation is not the result of changes in free-IAA levels.Abbreviations FR
far-red light
- IAA
indole-3-acetic acid
- Pfr
phytochrome in the far-red-absorbing form
- Pr
phytochrome in the red-absorbing form
- R
red light 相似文献
7.
Responses of strawberry plantlets cultured in vitro under superbright red and blue light-emitting diodes (LEDs) 总被引:1,自引:0,他引:1
Nhut Duong Tan Takamura T. Watanabe H. Okamoto K. Tanaka M. 《Plant Cell, Tissue and Organ Culture》2003,73(1):43-52
Unrooted strawberry cv. `Akihime' shoots with three leaves obtained from standard mixotrophic cultures were cultured in the ``Culture Pack'-rockwool system with sugar-free MS medium under CO2-enriched condition. To examine the effect of superbright red and blue light-emitting diodes (LEDs) on in vitro growth of plantlets, these cultures were placed in an incubator, ``LED PACK', with either red LEDs, red LEDs1blue LEDs or blue LEDs light source. To clarify the optimum blue and red LED ratio, cultures were placed in ``LED PACK 3' under LED light source with either 100, 90, 80, or 70% red + 0, 10, 20, 30% blue, respectively, and also under standard heterotrophic conditions. To determine the effects of irradiation level, cultures were grown under 90% red LEDs + 10% blue LEDs at 45, 60 or 75 mol m–2 s–1 . Plantlet growth was best at 70% red + 30% blue LEDs. The optimal light intensity was 60 mol m–2 s–1. Growth after transfer to soil was also best after in vitro culture with plantlets produced were 70% red LEDs + 30% blue LEDs. 相似文献
8.
The aim of the study was to determine the influence of total dissolvedsolids/salinity (mg L-1 TDS) on photosynthetic activity of Nodularia spumigena strain 001E isolated from Lake Alexandrina, SouthAustralia, using photosynthesis-irradiance (PI) curves. N. spumigena001E cultures were grown in ASM medium at a range of TDSconcentrations (360, 6,600, 13,200, 19,800, 26,400 mg L-1)at an irradiance of 30 mol m-2 s-1 (PAR, 400–700 nm) at 25 °C. The PI relationship was determined at 25 °Cfor irradiances between 0 and 500 mol photon m-2s-1 (PAR). The initial slope of PI curve, , a function of lightharvesting efficiency and photosynthetic energy conversion, decreasedproportionally with an increase in salinity from 360 to 26,400 mgL-1 TDS. The maximum rate of photosynthesis (Pmax),occurred at 6,600 mg L-1 TDS. No influence of salinity onIk, the irradiance at which Pmax was measured, or on Rd, the dark respiration rate, was identified. 相似文献
9.
T. I. Baskin 《Planta》1986,169(3):406-414
First positive phototropism of the third internode of intact, 5-d-old pea (Pisum sativum L.) seedlings, grown under continuous, dim red light, showed maximal response following a photon fluence of 3 mol·m-2 blue light. Greater or lesser fluences (with irradiation time 100 s or less) caused less bending, no response being detectable above 300 or below 0.03 mol·m-2. Bilateral irradiation with blue light caused no detectable inhibition of growth rate over that range of fluences. The linear nutation of the pea third internode was shown to be driven by a balanced oscillation of growth rate such that the overall growth rate was little changed during the oscillation. Phototropic stimulation changed neither the amplitude nor the period of nutation. Nutation and phototropism probably regulate growth independently. Phototropism in response to the optimal blue light fluence was caused by concomitant depressed growth on the irradiated side and stimulated growth on the shaded side of the bending internode. These results are consistent with the Cholodny-Went hypothesis which states that unilateral blue light induces a lateral redistribution of a growth regulator.Abbreviations R
red light
- BL
blue light
Carnegie Institution, Department of Plant Biology paper No. 921 相似文献
10.
Senescence-induced changes in the xanthophyll cycle activity and chlorophyll (Chl) fluorescence parameters were compared in detached barley (Hordeum vulgare L.) leaf segments kept for 6 d in darkness or under continuous white light (90 mol m–2 s–1). Before detachment of the leaf segments, the plants were grown at periodic regime [12 h light (90 mol m–2 s–1)/12 h dark]. The de-epoxidation state of the xanthophyll cycle pigments (DEPS) in the leaf samples was determined immediately (the actual DEPS), after 1 h of dark-adaptation (the residual DEPS), and during 14 min of a high-irradiance (HI) exposure (500 mol m–2 s–1) (HI-induced DEPS). In the light-senescing segments, senescence was delayed pronouncedly compared to dark-senescing ones as the Chl content, the photosystem 2 photochemistry, and electron transport processes were highly maintained. Further, the actual DEPS increased, probably due to the increased mean photon dose. The HI-induced increase in the DEPS was stimulated in the light-senescing segments, whereas it was slowed down in the dark-senescing ones. However, after the 14 min HI-exposure of the dark-senescing segments the HI-induced DEPS was not markedly lower than in the mature leaves, which indicated the maintenance of the xanthophyll cycle operation. 相似文献
11.
The responses to irradiance of photosynthetic CO2 assimilation and photosystem 2 (PS2) electron transport were simultaneously studied by gas exchange and chlorophyll (Chl) fluorescence measurement in two-year-old apple tree leaves (Malus pumila Mill. cv. Tengmu No.1/Malus hupehensis Rehd). Net photosynthetic rate (P
N) was saturated at photosynthetic photon flux density (PPFD) 600-1 100 (mol m-2 s-1, while the PS2 non-cyclic electron transport (P-rate) showed a maximum at PPFD 800 mol m-2 s-1. With PPFD increasing, either leaf potential photosynthetic CO2 assimilation activity (Fd/Fs) and PS2 maximal photochemical activity (Fv/Fm) decreased or the ratio of the inactive PS2 reaction centres (RC) [(Fi – Fo)/(Fm – Fo)] and the slow relaxing non-photochemical Chl fluorescence quenching (qs) increased from PPFD 1 200 mol m-2 s-1, but cyclic electron transport around photosystem 1 (RFp), irradiance induced PS2 RC closure [(Fs – Fo)/Fm – Fo)], and the fast and medium relaxing non-photochemical Chl fluorescence quenching (qf and qm) increased remarkably from PPFD 900 (mol m-2 s-1. Hence leaf photosynthesis of young apple leaves saturated at PPFD 800 mol m-2 s-1 and photoinhibition occurred above PPFD 900 mol m-2 s-1. During the photoinhibition at different irradiances, young apple tree leaves could dissipate excess photons mainly by energy quenching and state transition mechanisms at PPFD 900-1 100 mol m-2 s-1, but photosynthetic apparatus damage was unavoidable from PPFD 1 200 mol m-2 s-1. We propose that Chl fluorescence parameter P-rate is superior to the gas exchange parameter P
N and the Chl fluorescence parameter Fv/Fm as a definition of saturation irradiance and photoinhibition of plant leaves. 相似文献
12.
Alexander Ziegler-Jöns 《Planta》1989,178(2):164-175
Data for the maximum carboxylation velocity of ribulose-1,5-biosphosphate carboxylase, Vm, and the maximum rate of whole-chain electron transport, Jm, were calculated according to a photosynthesis model from the CO2 response and the light response of CO2 uptake measured on ears of wheat (Triticum aestivum L. cv. Arkas), oat (Avena sativa L. cv. Lorenz), and barley (Hordeum vulgare L. cv. Aramir). The ratio Jm/Vm is lower in glumes of oat and awns of barley than it is in the bracts of wheat and in the lemmas and paleae of oat and barley. Light-microscopy studies revealed, in glumes and lemmas of wheat and in the lemmas of oat and barley, a second type of photosynthesizing cell which, in analogy to the Kranz anatomy of C4 plants, can be designated as a bundle-sheath cell. In wheat ears, the CO2-compensation point (in the absence of dissimilative respiration) is between those that are typical for C3 and C4 plants.A model of the CO2 uptake in C3–C4 intermediate plants proposed by Peisker (1986, Plant Cell Environ. 9, 627–635) is applied to recalculate the initial slopes of the A(pc) curves (net photosynthesis rate versus intercellular partial pressure of CO2) under the assumptions that the Jm/Vm ratio for all organs investigated equals the value found in glumes of oat and awns of barley, and that ribulose-1,5-bisphosphate carboxylase is redistributed from mesophyll to bundle-sheath cells. The results closely match the measured values. As a consequence, all bracts of wheat ears and the inner bracts of oat and barley ears are likely to represent a C3–C4 intermediate type, while glumes of oat and awns of barley represent the C3 type.Abbreviations A
net photosynthesis rate (mol·m-2·s-1)
- Jm
maximum rate of whole-chain electron transport (mol·e-·m-2·s-1)
- pc (bar)
intercellular partial pressure of CO2
- PEP
phosphoenolpyruvate
- PPFD
photosynthetic photon flux density (mol quanta·m-2·s-1)
- RuBPCase
ribulose bisphosphate carboxylase/oxygenase
- RuBP
ribulose bisphosphate
- Vm
maximum carboxylation velocity of RuBPCase (mol·m-2·s-1)
- T*
CO2 compensation point in the absence of dissimilative respiration (bar) 相似文献
13.
Desana Li >sková José Ruiz Ordóñez Alexander Lux Alfredo Piñeyro López 《Plant Cell, Tissue and Organ Culture》1994,36(3):339-343
Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10-2 mol l–1, gibberellic acid (GA3) 3.10-2 mol l–1, and 6-benzylaminopurine (BA) 2 mol l–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l–1, GA3 14 mol l–1, and kinetin 5 mol l–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l–1 and BA 10 mol l–1 was induced.Abbreviations BA
6-benzylaminopurine
- 2,4-d
2,4-dichlorophenoxyacetic acid
- GA3
gibberellic acid
- IAA
indole-3-acetic acid
- NAA
1-naphthaleneacetic acid
- TEM
transmission electron microscopy 相似文献
14.
The effect of light on the metabolism of ammonia was studied by subjecting detached maize leaves to 150 or 1350 mol m–2 s–1 PAR during incubation with the leaf base in 2 mM 15NH4Cl. After up to 60 min, leaves were extracted. Ammonia, glutamine, glycine, serine, alanine, and aspartate were separated by isothermal distillation and ion exchange chromatography. 15N enrichments were analyzed by emission spectroscopy. The uptake of ammonium chloride did not influence CO2 assimilation (8.3 and 17.4 mol m–1 s–1 at 150 and 1350 mol m–2 s–1 PAR, respectively). Leaves kept at high light intensity contained more serine and less alanine than leaves from low light treatments. Within 1 h of incubation the enrichment of ammonia extracted from leaves rose to approximately 20% 15N. In the high light regime the amino acids contained up to 15% 15N, whereas in low light 15N enrichments were small (up to 6%). The kinetics of 15N incorporation indicated that NH3 was firstly assimilated into glutamine and then into glutamate. After 15 min 15N was also found in glycine, serine and alanine. At high light intensity nearly half of the 15N was incorporated in glycine. On the other hand, at low light intensity alanine was the predominant 15N sink. It is concluded that light influences ammonia assimilation at the glutamine synthetase reaction. 相似文献
15.
Sulphate uptake by the unicellular marine red algaRhodella maculata conforms to Michaelis-Menten kinetics. Two uptake systems have been found: a low affinity system with an apparentK
m
of 22 mM, and a high affinity system with an apparentK
m
of 63.4 M. Transition from the low to the high affinity system can occur within 2.5 min, in response to a decrease in the ambient sulphate concentration to below 10 mM. Assimilation rates in the dark are about 20% those in the light, although enhancement by light is independent of the quanlity of light supplied above 27 mol m-2 s-1. Use of metabolic inhibitors indicates that photophosphorylation provides the main source of energy for sulphate assimilation, through both cyclic and non-cyclic electron flow.Abbreviations used APS-kinase
ATP:adenylyl-sulphate 3-phosphotransferase (E.C. 2.7.1.25)
- ATP-sulphurylase
ATP:sulphate adenylyltransferase (E.C.2.7.74)
- DCMU
[3-(3,4-dichlorophenyl)]-1,1 dimethylurea
- 2,4 DNP
2,4-dinitrophenol
- DBMIB
Dibromothymoquinone (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone) 相似文献
16.
The influence of far-red (FR; 700–800 nm) radiation on steady-state stomatal conductance and net photosynthesis in P. vulgaris has been studied. Whereas FR radiation alone was relatively ineffective, addition of FR to a background of white light (WL; predominantly 400–700 nm) resulted in increased stomatal conductance. Stomata exhibited a marked diurnal sensitivity to FR. The action maximum for enhancing stomatal conductance was near 714 nm. A combination of FR and infra-red (IR; >800 nm) enhanced net photosynthesis when added to a background of WL. When IR alone was added to WL, there was a net decrease in photosynthesis, indicating that it is the FR waveband which is responsible for the observed photosynthetic effects. Naturally occurring levels of FR radiation (235 mol·m-2·s-1) in vegetation-canopy shade enhanced net photosynthetic CO2 gain by 28% when added to a background of 55 mol·m-2·s-1 WL.Abbreviations BL
blue
- FR
far-red
- IR
infra-red
- PAR
photosynthetically active radiation
- R
red
- WL
white light 相似文献
17.
The role of oxygen in the photoinactivation of the photosynthetic apparatus of Spinacia oleracea L. was investigated. Moderate irradiation (1200 mol photons m-2s-1) of spinach leaves in an atmosphere of pure nitrogen caused strong inhibition of subsequently measured net CO2 assimilation, whereas considerably less photoinhibition was observed in the presence of low partial pressures (10–20 mbar) of O2. The decrease in activity caused by anaerobiosis in the light was not based on stomatal closure; the decline of assimilation represents a photoinhibition, as activity was not impaired by low irradiation (80 mol photos m-2s-1). In contrast, gassing with pure N2 in the dark caused strong inhibition. Electron-transport rates and chlorophyll-fluorescence data of thylakoids isolated from photoinhibited leaves indicated damage to the electron-transport system, in particular to photosystem II reaction centers. In vitro, photoinhibition in isolated thylakoid membranes was also strongly promoted by anaerobiosis. Photoinhibition of electron-transport rates under anaerobic conditions was characterized by a pronounced increase in the initial fluorescence level, F0, of chlorophyll-fluorescence induction, in contrast to photoinhibition under aerobic conditions. The results are discussed in terms of two mechanisms of photoinhibition, one that is suppressed and a second that is promoted by oxygen.Abbreviations Chl
chlorophyll
- DCMU
3-(3, 4-dichlorophenyl)-1,1-dimethylurea
- PSI, II
photosystem I, II 相似文献
18.
A. J. Soitamo G. Zhou A. K. Clarke G. Öquist P. Gustafsson E. M. Aro 《Plant molecular biology》1996,30(3):467-478
Over-expression of the psbAIII gene encoding for the D1 protein (form II; D1:2) of the photosystem II reaction centre in the Synechococcus sp. PCC 7942 was studied using a tac promoter and the lacI
Q system. Over-expression was induced with 40 g/ml IPTG in the growth medium for either 6 or 12 h at growth irradiance (50 mol photons m-2 s-1). This treatment doubled the amount of psbAII/III mRNA and the D1:2 protein in membranes but decreased the amount of psbAI messages and the D1:1 protein. The total amount of both heterodimeric reaction centre proteins, D1 and D2, remained constant under growth light conditions, indicating that the number of PSII centres in the membranes was not affected, only the form of the D1 protein was changed from D1:1 to D1:2 in most centres. When the cells were photoinhibited either at 500 or 1000 mol photons m-2 s-1, in the presence or absence of the protein synthesis inhibitor lincomycin, the D1:2 protein remained at a higher level in cells in which over-expression had been induced by IPTG. These cells were also less prone to photoinhibition of PSII. It is suggested that the tolerance of cells to photoinhibition increases when most PSII reaction centres contain the D1:2 protein at the beginning of high irradiance. This tolerance is further strengthened by maintaining psbAIII gene over-expression during the photoinhibitory treatment. 相似文献
19.
Shi Tan Gregory R. Wolfe Francis X. Cunningham Jr Elisabeth Gantt 《Photosynthesis research》1995,45(1):1-10
Thylakoids isolated from cells of the red alga Porphyridium cruentum exhibit an increased PS I activity on a chlorophyll basis with increasing growth irradiance, even though the stoichiometry of Photosystems I and II in such cells shows little change (Cunningham et al. (1989) Plant Physiol 91: 1179–1187). PS I activity was 26% greater in thylakoids of cells acclimated at 280 mol photons · m–2 · s–1 (VHL) than in cells acclimated at 10 mol photons · m–2 · s–1 (LL), indicating a change in the light absorbance capacity of PS I. Upon isolating PS I holocomplexes from VHL cells it was found that they contained 132±9 Chl/P700 while those obtained from LL cells had 165±4 Chl/P700. Examination of the polypeptide composition of PS I holocomplexes on SDS-PAGE showed a notable decrease of three polypeptides (19.5, 21.0 and 22 kDa) in VHL-complexes relative to LL-complexes. These polypeptides belong to a novel LHC I complex, recently discovered in red algae (Wolfe et al. (1994a) Nature 367: 566–568), that lacks Chl b and includes at least six different polypeptides. We suggest that the decrease in PS I Chl antenna size observed with increasing irradiance is attributable to changes occurring in the LHC I-antenna complex. Evidence for a Chl-binding antenna complex associated with PS II core complexes is lacking at this point. LHC II-type polypeptides were not observed in functionally active PS II preparations (Wolfe et al. (1994b) Biochimica Biophysica Acta 1188: 357–366), nor did we detect polypeptides that showed immunocross-reactivity with LHC II specific antisera (made to Chlamydomonas and Euglena LHC II).Abbreviations Bis-Tris
bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane
- DCPIP
2,6-dichlorophenol indophenol
- -dm
dodecyl--d-maltoside
- HL
high light of 150 mol photons · m–2 · s–1
- LGB
lower green band
- LHC I
light-harvesting complex of PS I
- LHC II
light-harvesting complex of PS II
- LL
low light of 10 mol photons · m–2 · s–1
- ML
medium light of 50 mol photons · m–2 · s–1
- MES
2-(N-morpholino) ethanesulfonic acid
- P700
reaction center of PS I
- PFD
photon flux density
- Trizma
tris(hydroxymethyl)aminomethane
- UGB
upper green band
- VHL
very high light of 280 mol photons · m–2 · s–1 相似文献
20.
Leaf photosynthetic rates were measured on field-grown soybeans during the 1980 season. Comparisons were made between different cultivars and isolines representative of maturity groups I–IV. Mature, fully expanded leaves at different nodes on the plant were measured in high light to determine which had the highest potential photosynthetic rates at any one time. Successive leaves during the growing season had maximum rates which increased from about 22 mol CO2 m-2 s-1 on 25 June to a peak of 30–44 mol CO2 m-2 s-1 in early August.The persistency and eventual decline in the maximum rate was associated with the maturity group and related dates of flowering, pod fill and onset of senescence. Early maturing cultivars (groups I and II) had higher peak rates (38–44 mol CO2 m-2 s-1) than later maturing cultivars (30–35 mol CO2 m-2 s-1, groups III and IV). However, the photosynthetic rates of early maturing cultivars declined rapidly after attaining their peak, whereas the leaves of later maturing cultivars maintained their photosynthetic activity for much longer. 相似文献