The Leafless Orchid Cymbidium macrorhizon Performs Photosynthesis in the Pericarp during the Fruiting Season

2021 ◽  
Author(s):  
Koichi Kobayashi ◽  
Kenji Suetsugu ◽  
Hajime Wada
Keyword(s):  
Electron Transport ◽  
Mycorrhizal Fungi ◽  
Significant Proportion ◽  
Photochemical Efficiency ◽  
Fluorescence Analysis ◽  
Photosynthetic Electron Transport ◽  
Isotopic Analysis ◽  
Fluorescence Induction ◽  
Induction Kinetics ◽  
Chl Fluorescence

Abstract Photosynthesis with highly photoreactive chlorophyll (Chl) provides energy for plant growth but with simultaneous risk of photooxidative damage and photoprotection costs. Although the leafless orchid Cymbidium macrorhizon mostly depends on mycorrhizal fungi for carbon, it accumulates Chl particularly during fruiting and may not be fully mycoheterotrophic. In fact, stable isotopic analysis suggested that the fruiting C. macrorhizon specimens obtain a significant proportion of its carbon demands through photosynthesis. However, actual photosynthetic characteristics of this leafless orchid are unknown. To reveal the functionality of photosynthetic electron transport in C. macrorhizon, we compared its photosynthetic properties with those of its relative mixotrophic orchid Cymbidium goeringii and the model plant Arabidopsis thaliana. Compared with C. goeringii and A. thaliana, maximum photochemical efficiency of PSII was substantially low in C. macrorhizon. Chl fluorescence induction kinetics revealed that the electron transport capacity of PSII was limited in C. macrorhizon. Chl fluorescence analysis at 77 K suggested partial energetic disconnection of the light-harvesting antenna from the PSII reaction center in C. macrorhizon. Despite its low PSII photochemical efficiency, C. macrorhizon showed photosynthetic electron transport activity both in the field and under laboratory conditions. Cymbidium macrorhizon developed strong nonphotochemical quenching in response to increased light intensity as did C. goeringii, suggesting the functionality of photoprotective systems in this orchid. Moreover, C. macrorhizon fruit developed stomata on the pericarp and showed net O2-evolving activity. Our data demonstrate that C. macrorhizon can perform photosynthetic electron transport in the pericarp, although its contribution to net carbon acquisition may be limited.

scholarly journals Irradiance and nutrient-dependent effects on photosynthetic electron transport in Arctic phytoplankton: A comparison of two chlorophyll fluorescence-based approaches to derive primary photochemistry

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0256410
Author(s):  
Yayla Sezginer ◽  
David J. Suggett ◽  
Robert W. Izett ◽  
Philippe D. Tortell
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Electron Transport Rate ◽  
Photochemical Efficiency ◽  
Photosynthetic Electron Transport ◽  
Marine Phytoplankton ◽  
Transport Rate ◽  
Variable Fluorescence ◽  
Primary Photochemistry ◽  
Electron Transport Rates

We employed Fast Repetition Rate fluorometry for high-resolution mapping of marine phytoplankton photophysiology and primary photochemistry in the Lancaster Sound and Barrow Strait regions of the Canadian Arctic Archipelago in the summer of 2019. Continuous ship-board analysis of chlorophyll a variable fluorescence demonstrated relatively low photochemical efficiency over most of the cruise-track, with the exception of localized regions within Barrow Strait, where there was increased vertical mixing and proximity to land-based nutrient sources. Along the full transect, we observed strong non-photochemical quenching of chlorophyll fluorescence, with relaxation times longer than the 5-minute period used for dark acclimation. Such long-term quenching effects complicate continuous underway acquisition of fluorescence amplitude-based estimates of photosynthetic electron transport rates, which rely on dark acclimation of samples. As an alternative, we employed a new algorithm to derive electron transport rates based on analysis of fluorescence relaxation kinetics, which does not require dark acclimation. Direct comparison of kinetics- and amplitude-based electron transport rate measurements demonstrated that kinetic-based estimates were, on average, 2-fold higher than amplitude-based values. The magnitude of decoupling between the two electron transport rate estimates increased in association with photophysiological diagnostics of nutrient stress. Discrepancies between electron transport rate estimates likely resulted from the use of different photophysiological parameters to derive the kinetics- and amplitude-based algorithms, and choice of numerical model used to fit variable fluorescence curves and analyze fluorescence kinetics under actinic light. Our results highlight environmental and methodological influences on fluorescence-based photochemistry estimates, and prompt discussion of best-practices for future underway fluorescence-based efforts to monitor phytoplankton photosynthesis.

The Inhibition of Photosynthetic Electron Transport by DBMIB and its Restoration by p-Phenylenediamines; Studied by Means of Prompt and Delayed Chlorophyll Fluorescence of Green Algae

1974 ◽  
Vol 29 (11-12) ◽  
pp. 725-732 ◽  
Author(s):  
Robert Bauer ◽  
Mathijs J. G. Wijnands
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Photosynthetic Electron Transport ◽  
Primary Electron ◽  
Delayed Fluorescence ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Exchange Reactions ◽  
Redox Systems

Abstract The effect of the plastohydroquinone antagonist dibromothym oquinone (DBMIB) on photosynthetic electron transport reactions was studied in the presence and absence of p-phenylene-diamines by means of measurements of prompt and delayed chlorophyll fluorescence induction of the green alga Scenedesm us obliquus. Prompt and delayed chlorophyll fluorescence induction phenomena are valid indicators for the native presence of and cooperation between the two photosynthetic light reactions. Their kinetics reflect the balancing of electron exchange reactions in the chain of coupled redox-systems between the two photosystems upon sudden illumination. From distinct alterations of the short-term (sec) light induced changes in the yield of prom pt and delayed chlorophyll fluorescence it is concluded that DBMIB inhibits the photosynthetic electron transport in the chain of redox-systems between the two light reactions. There is evidence to show that upon illumination of DBMIB treated cells only the reduction of primary electron ac­ceptor pools of photosystem II (i. e. Q and PQ) is still possible. After their reduction the further electron transport through photosystem II is blocked. The addition of p-phenylenediamines to DBM IB-treated cells abolishes the typical DBMIB-affected prom pt and delayed fluorescence inhibition curves and the normal induction curves re­ appear qualitatively in all their important features. From these measurements it is suggested that the redox properties of p-phenylenediamines allow an electron transport bypass of the DBMIB inhibition site which results in a fully restored photosynthetic electron transport from water to NADP.

scholarly journals Salt Priming Protects Photosynthetic Electron Transport against Low-Temperature-Induced Damage in Wheat

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 62 ◽  
Author(s):  
Hui Li ◽  
Huawei Li ◽  
Yanjie Lv ◽  
Yongjun Wang ◽  
Zongshuai Wang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Low Temperature ◽  
Reaction Center ◽  
Early Stage ◽  
Photochemical Efficiency ◽  
Photosynthetic Electron Transport ◽  
Nacl Solution ◽  
Wheat Seedlings ◽  
Germinating Seeds ◽  
Salt Priming

Low temperature limits the photochemical efficiency of photosystems in wheat plants. To test the effect of salt priming on the photosynthetic electron transport in wheat under low temperature, the germinating seeds of a winter wheat cv. Jimai44 were primed with varying concentrations of NaCl solutions (0, 10, 30, and 50 mM NaCl, indicated by S0, S10, S30, and S50, respectively) for 6 d, and after 11 d of recovery, the seedlings were subsequently exposed to 24-h low-temperature stress (2 °C). Under low temperature, the S30 plants possessed the highest absorption flux per reaction center and higher density of reaction center per cross-section among the treatments. In addition, S30 plants had higher trapped energy flux for reducing QA and fraction of QA-reducing reaction centers and non-QB reducing center than the non-primed plants under low temperature, indicating that S30 plants could maintain the energy balance of photosystems and a relatively higher maximum quantum efficiency of photosystem II under low temperature. In addition, the low temperature-induced MDA accumulation and cell death were alleviated by salt priming in S30 plants. It was suggested that salt priming with an optimal concentration of NaCl solution (30 mM) during seed germination enhanced the photochemical efficiency of photosystems in wheat seedlings, which could be a potential approach to improve cold tolerance in wheat at an early stage.

Inhibition of quantum yield of PS II electron transport in Spirulina platensis by osmotic stress may be explained mainly by an increase in the proportion of the QB-non-reducing PS II reaction centres

1998 ◽  
Vol 25 (6) ◽  
pp. 689 ◽  
Author(s):  
Congming Lu ◽  
Jianhua Zhang ◽  
Avigad Vonshak
Keyword(s):  
Electron Transport ◽  
Quantum Yield ◽  
Osmotic Stress ◽  
Spirulina Platensis ◽  
Fluorescence Induction ◽  
Photochemical Quenching ◽  
Ps Ii ◽  
Reaction Centres ◽  
Induction Kinetics ◽  
Fluorescence Induction Kinetics

Modulated chlorophyll fluorescence and fluorescence induction kinetics were used to evaluate the PS II photochemistry in Spirulina platensis exposed to osmotic stress (0–0.8 M mannitol). Osmotic stress decreased the efficiency of excitation energy capture by open PS II reaction centres (Fv′/Fm′) and more significantly, decreased photochemical quenching (qP). Osmotic stress also decreased the maximal efficiency of PS II photochemistry (Fv/Fm). There was no significant change in non-photochemical quenching (qN), indicating that the decreased Fv′/Fm′ was not due to an increase in qN. Analyses of the fast fluorescence induction kinetics indicated that osmotic stress caused a significant increase in the proportion of the QB-non-reducing PS II reaction centres. Based on the results in this study, we suggest that a substantial increase in the proportion of the QB-non-reducing PS II reaction centres may be responsible for the decrease in qP and Fv′/Fm′, of which both resulted in the decrease in the quantum yield of PS II electron transport (ΦPSII ).

Effects of Pyridate on Chickpea

1995 ◽  
Vol 22 (5) ◽  
pp. 731 ◽  
Author(s):  
R Gimeenez-Espinosa ◽  
R Jimenez-Diaz ◽  
RD Prado
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Fluorescence Intensity ◽  
Active Ingredient ◽  
Photosynthetic Activity ◽  
Photosynthetic Electron Transport ◽  
Fluorescence Induction ◽  
Hill Reaction ◽  
Lolium Rigidum ◽  
Cicer Arietinum L

The effects of pyridate on 15 different chickpea (Cicer arietinum L.) genotypes have been investigated under controlled environmental conditions. Different degrees of tolerance to pyridate were detected. Pyridate applied at 2.0 and 4.0 kg active ingredient ha-1 inhibited the growth of two of the 15 genotypes. Chlorophyll fluorescence intensity showed high levels of inhibition 3 h after treatment in chickpea. For all the genotypes, photosynthetic activity was recovered 10 days after treatment. Fluorescence-induction curves revealed that pyridate inhibited photosynthetic electron transport in chickpea genotypes and Amaranthus blitoides faster than in Lolium rigidum. Photosynthesis in chickpea genotypes recovered more quickly than in Lolium rigidum, while Amaranthus blitoides died 3 days after treatment. Hill reaction assays concluded that CL9673 was the most phytotoxic pyridate metabolite. The order of phytotoxicity was CL9673 >> CL9673-N-Gly > CL9869 > pyridate > CL9673-O-Gly. These results support the idea that tolerance of chickpea to pyridate is due to degradation and detoxification of the herbicide.

Determination of Herbicide Inhibition of Photosynthetic Electron Transport by Fluorescence

Weed Science ◽  
1983 ◽  
Vol 31 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Edward P. Richard ◽  
John R. Goss ◽  
Charles J. Arntzen ◽  
Fred W. Slife
Keyword(s):  
Electron Transport ◽  
Foliar Application ◽  
Photosynthetic Electron Transport ◽  
Fluorescence Measurements ◽  
Abaxial Leaf Surface ◽  
Terminal Level ◽  
Non Destructive ◽  
Kinetics Of ◽  
Chl Fluorescence

The kinetics of chlorophyll (Chl) fluorescence was used as a tool for detecting herbicide inhibition in studies using intact soybean [Glycine max(L.) Merr.] leaves. The terminal level of fluorescence (FT), obtained 150 s after the onset of illumination of the abaxial leaf surface, was found to be independent of the dark preadaptation interval and to vary little between leaflets and leaves within and among untreated plants. Increases in FTwere detected in plants following the foliar application of herbicides which inhibit photosynthetic electron transport. Fluorescence measurements indicated significant electron transport inhibition in leaves following treatment with 40-mM solutions of either atrazine [2-chloro-4-(ethylamino)-6-(isopropyiamino)-s-triazine] or diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] after 0.5 and 1 h, respectively. Results of this study indicate that Chl fluorescence can be used to measure injury qualitatively by photosynthetic electron transport-inhibiting herbicides in intact plants long before visual symptoms of injury occur. Possible uses of this sensitive, rapid, and non-destructive technique for studying herbicide penetration as affected by adjuvants and environmental factors are discussed.

scholarly journals Respiration Interacts With Photosynthesis Through the Acceptor Side of Photosystem I, Reflected in the Dark-to-Light Induction Kinetics of Chlorophyll Fluorescence in the Cyanobacterium Synechocystis sp. PCC 6803

2021 ◽  
Vol 12 ◽  
Author(s):  
Takako Ogawa ◽  
Kenta Suzuki ◽  
Kintake Sonoike
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Photosystem I ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Light Induction ◽  
Acceptor Side ◽  
Induction Kinetics ◽  
Electron Transport Chains ◽  
Kinetics Of

In cyanobacteria, the photosynthetic prokaryotes, direct interaction between photosynthesis and respiration exists at plastoquinone (PQ) pool, which is shared by the two electron transport chains. Another possible point of intersection of the two electron transport chains is NADPH, which is the major electron donor to the respiratory chain as well as the final product of the photosynthetic chain. Here, we showed that the redox state of NADPH in the dark affected chlorophyll fluorescence induction in the cyanobacterium Synechocystis sp. PCC 6803 in a quantitative manner. Accumulation of the reduced NADPH in the dark due to the defect in type 1 NAD(P)H dehydrogenase complex in the respiratory chain resulted in the faster rise to the peak in the dark-to-light induction of chlorophyll fluorescence, while depletion of NADPH due to the defect in pentose phosphate pathway resulted in the delayed appearance of the initial peak in the induction kinetics. There was a strong correlation between the dark level of NADPH determined by its fluorescence and the peak position of the induction kinetics of chlorophyll fluorescence. These results indicate that photosynthesis interacts with respiration through NADPH, which enable us to monitor the redox condition of the acceptor side of photosystem I by simple measurements of chlorophyll fluorescence induction in cyanobacteria.

scholarly journals Chlorophyll fluorescence-based estimates of photosynthetic electron transport in Arctic phytoplankton assemblages

2021 ◽  
Author(s):  
Yayla Sezginer ◽  
David J. Suggett ◽  
Robert W. Izett ◽  
Philippe D. Tortell
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Electron Transport Rate ◽  
Photochemical Efficiency ◽  
Photosynthetic Electron Transport ◽  
Marine Phytoplankton ◽  
Transport Rate ◽  
Photochemical Quenching ◽  
Variable Fluorescence ◽  
Electron Transport Rates

AbstractWe employed Fast Repetition Rate fluorometry for high-resolution mapping of marine phytoplankton photophysiology and primary productivity in the Lancaster Sound and Barrow Strait regions of the Canadian Arctic Archipelago in the summer of 2019. Continuous ship-board analysis of chlorophyll a variable fluorescence demonstrated relatively low photochemical efficiency over most of the cruise-track, with the exception of localized regions within Barrow Strait where there was increased vertical mixing and proximity to land-based nutrient sources. Along the full transect, we observed strong non-photochemical quenching of chlorophyll fluorescence, with relaxation times longer than the 5-minute period used for dark acclimation. Such long-term quenching effects complicate continuous underway acquisition of fluorescence amplitude-based estimates of photosynthetic electron transport rates, which rely on dark acclimation of samples. As an alternative, we employed a new algorithm to derive electron transport rates based on analysis of fluorescence relaxation kinetics, which does not require dark acclimation. Direct comparison of kinetics- and amplitude-based electron transport rate measurements demonstrated kinetic-based estimates were, on average, 2-fold higher than amplitude-based values. The magnitude of decoupling between the two electron transport rate estimates increased in association with photophysiological diagnostics of nutrient stress. Discrepancies between electron transport rate estimates likely resulted from the use of different photophysiological parameters to derive the kinetics- and amplitude-based algorithms, and choice of numerical model used to fit variable fluorescence curves and analyze fluorescence kinetics under actinic light. Our results highlight environmental and methodological influences on fluorescence-based productivity estimates, and prompt discussion of best-practices for future underway fluorescence-based efforts to monitor phytoplankton photosynthesis.

scholarly journals Effect of cobalt on growth, pigments and the photosynthetic electron transport in Monoraphidium minutum and Nitzchia perminuta

2003 ◽  
Vol 15 (3) ◽  
pp. 159-166 ◽  
Author(s):  
M.M. El-Sheekh ◽  
A.H. El-Naggar ◽  
M.E.H. Osman ◽  
E. El-Mazaly
Keyword(s):  
Electron Transport ◽  
Algal Species ◽  
Photosynthetic Electron Transport ◽  
Experimental Period ◽  
Fluorescence Induction ◽  
O2 Evolution ◽  
O2 Uptake ◽  
Acceptor Side ◽  
Low Co2 ◽  
Co2 Concentrations

The unicellular green alga Monoraphidium minutum and the diatom Nitzschia perminuta were cultured under different concentrations of Co2+. Growth and pigment content were slightly increased at low concentrations and inhibited by high Co2+ concentrations. The results concerning the effect of different concentrations of Co2+ on photosynthetic O2 evolution showed a reduction in the amount of O2 evolved by each alga in response to increasing Co2+ concentrations. However, an increase in O2 evolution for both M. minutum and N. perminuta was observed at relatively low Co2+ concentrations. Photosynthetic electron transport in M. minutum was more sensitive to Co2+ toxicity than in N. perminuta. On the other hand, the effect of the heavy metal on respiration showed that higher Co2+ concentrations were inhibitory to O2 uptake by the two algal species. Low Co2+ concentrations stimulated O2 uptake by M. minutum throughout the experimental period. However, in N. perminuta, different concentrations of Co2+ led to a reduction of O2 uptake. To localize the action site of Co2+ in the photosynthetic electron transport chain, the fluorescence induction technique was carried out. According to the results obtained, the inhibitory action of Co2+ is located on the acceptor side of PSII for both M. minutum and N. perminuta.

Sign in / Sign up

Export Citation Format

Share Document