scholarly journals Methyl Jasmonate Protects the PS II System by Maintaining the Stability of Chloroplast D1 Protein and Accelerating Enzymatic Antioxidants in Heat-Stressed Wheat Plants

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1216
Author(s):  
Mehar Fatma ◽  
Noushina Iqbal ◽  
Zebus Sehar ◽  
Mohammed Nasser Alyemeni ◽  
Prashant Kaushik ◽  
...  
Keyword(s):  
Heat Stress ◽  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Methyl Jasmonate ◽  
Reaction Center ◽  
D1 Protein ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Enzymatic Antioxidants ◽  
Ps Ii

The application of 10 µM methyl jasmonate (MeJA) for the protection of wheat (Triticum aestivum L.) photosystem II (PS II) against heat stress (HS) was studied. Heat stress was induced at 42 °C to established plants, which were then recovered at 25 °C and monitored during their growth for the study duration. Application of MeJA resulted in increased enzymatic antioxidant activity that reduced the content of hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS) and enhanced the photosynthetic efficiency. Exogenous MeJA had a beneficial effect on chlorophyll fluorescence under HS and enhanced the pigment system (PS) II system, as observed in a JIP-test, a new tool for chlorophyll fluorescence induction curve. Exogenous MeJA improved the quantum yield of electron transport (ETo/CS) as well as electron transport flux for each reaction center (ET0/RC). However, the specific energy fluxes per reaction center (RC), i.e., TR0/RC (trapping) and DI0/RC (dissipation), were reduced by MeJA. These results indicate that MeJA affects the efficiency of PS II by stabilizing the D1 protein, increasing its abundance, and enhancing the expression of the psbA and psbB genes under HS, which encode proteins of the PS II core RC complex. Thus, MeJA is a potential tool to protect PS II and D1 protein in wheat plants under HS and to accelerate the recovery of the photosynthetic capacity.

scholarly journals Some special features of the water regime and the photosynthetic apparatus activity in Feijoa sellowiana (O. Berg) O. Berg plants under the water stress

2021 ◽  
Vol 38 ◽  
pp. 00117
Author(s):  
Elena Shishkina ◽  
Tatiyna Gubanova ◽  
Valerii Titov
Keyword(s):  
Chlorophyll Fluorescence ◽  
Water Stress ◽  
Drought Tolerance ◽  
Water Content ◽  
Water Regime ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Ps Ii ◽  
Water Stress Tolerance ◽  
Leaf Tissues

When assessing the drought tolerance of Feijoa sellowiana cultivars and forms, the total water content in leaf tissues and their waterretaining and regenerative capacity were determined, and the parameters of chlorophyll fluorescence induction were measured at different water content in leaves. Current-year leaves were characterized by a higher sensitivity to drought. According to the complex of water regime parameters and characteristics of the chlorophyll fluorescence induction (CFI), it was found that the cultivar Aromatnaya Fantazia and the form 3/1 are characterized by a relatively high drought tolerance. It has been demonstrated that the common method for assessing plant tolerance by the index of their water-retaining forces, in relation to Feijoa sellowiana genotypes, does not allow determining the critical level of water deficit. It has been found that in the cultivars and forms with low water stress tolerance, with the water loss of 20-25% from the leaf tissues complete hydration, irreversible irregularities in the PS II structures occurred. The most sensitive to the lack of water in the leaves were such parameters as variable fluorescence, rate constants of the photochemical and non-photochemical deactivation of the excitation, as well as the processes of Qa reduction in the reaction centers of PS II.

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 Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient

2013 ◽  
Vol 3 (2) ◽  
pp. 163-172 ◽  
Author(s):  
David Miguel Vilumbrales ◽  
Kateřina Skácelová ◽  
Miloš Barták
Keyword(s):  
Energy Transfer ◽  
Salt Stress ◽  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Excitation Energy ◽  
Reaction Center ◽  
Excitation Energy Transfer ◽  
Ps Ii ◽  
Fluorescence Transient ◽  
Chlorophyll Fluorescence Transient

In this study, we investigated the effects of salt stress (2 mM NaCl) on excitation energy transfer from light harvesting complexes to photosystem II (PS II) in two Antarctic algal species: Klebsormidium sp. and Zygnema sp. Short-term salt stress led to a significant changes in the shape of chlorophyll fluorescence transient (OJIP). Analyses of the polyphasic fluorescence transients (OJIP) showed that the fluorescence yield at the phases J, I and P declined considerably with the time of exposition to salt stress. In both experimental species, OJIP transients reached lowest values of chlorophyll fluorescence signal after 30/60 min. of NaCl exposition. Then, OJIP shape and chlorophyll fluo-rescence showed species-specific recovery and rised towards original values (about 2/3 of untreated control). Analyses of chlorophyll fluorescence parameters derived from OJIPs showed that salt stress led to a decrease in the maximal efficiency of PS II photo-chemistry (FV/FM) in Zygnema sp. but not Klebsormidium sp. The results indicated that the probability of excitation energy transfer before and beyond QA, and the yield of electron transport beyond QA is limited by salt-induced stress in Zygnema sp. In addition, salt stress resulted in a decrease in the photosynthetic electron transport per PS II reaction center, but both increase and decrease in the trapping per PS II reaction center was found. Performace index (PIabs) was affected negatively in Zygnema sp. but possitively Klebsormidium sp. indicating that the latter species was more resistant to salt stress than Zygnema sp.

Chlorophyll fluorescence induction: an indicator of photosynthetic activity in marine algae undergoing desiccation

1978 ◽  
Vol 56 (21) ◽  
pp. 2787-2794 ◽  
Author(s):  
James Wiltens ◽  
Ulrich Schreiber ◽  
William Vidaver
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Water Content ◽  
High Tide ◽  
Net Photosynthesis ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Physiological Basis ◽  
Value Analysis

Algae of higher intertidal regions tend to be tolerant of extended periods of desiccation, while many lower tidal or subtidal species do not withstand even mild water loss. (Tidal regions can be characterized as high (regularly immersed at high tide and exposed at low tide), low (emergence only during minus tides (lower than mean low tide)), or subtidal (never exposed at low tide and extending to the maximum depth at which net photosynthesis can occur).) The ecological necessity for tolerance in frequently emerged species is obvious, but the physiological basis of it is not well understood. Changes of photosynthetic partial reactions upon desiccation and rehydration of tolerant and sensitive algae were studied by measurements of chlorophyll fluorescence induction kinetics (Kautsky effect). With progressive decrease in water content the gradual disappearance of the characteristic fluorescence transients was observed in both tolerant and sensitive species. The water content ranges where typical changes occurred were species dependent. Rehydration in tolerant plants resulted in rapid recovery from severe desiccation; there was no such recovery in sensitive plants when water content was decreased below a critical value. Analysis of the fluorescence changes upon desiccation and rehydration suggests: (1) electron transport between photosystem II and photosystem I, as well as H2O splitting are the partial reactions sensitive to desiccation; (2) in the resistant Porphyra sanjuanensis, intersystem electron transport is blocked at around 25% water content; (3) further desiccation leads to loss of water-splitting activity and eventually to the complete loss of variable fluorescence photosystem II reaction centers; and (4) on rehydration intersystem electron transport begins almost immediately while recovery of H2O splitting requires several minutes.

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.

Hydrostatic Pressure: A Reversible Inhibitor of Primary Photosynthetic Processes

1973 ◽  
Vol 28 (11-12) ◽  
pp. 704-709 ◽  
Author(s):  
Ulrich Schreiber ◽  
William Vidaver
Keyword(s):  
Chlorophyll Fluorescence ◽  
Hydrostatic Pressure ◽  
Fluorescence Induction ◽  
Oxygen Exchange ◽  
Pressure Effects ◽  
Chlorophyll Fluorescence Induction ◽  
Reversible Inhibitor ◽  
Ps Ii ◽  
System Pressure ◽  
Fluorescence Rise

Abstract Primary photosynthetic processes under pressures of up to 1300 atm were studied by means of chlorophyll fluorescence induction (Kautsky-effect) and compared to simultaneous oxygen exchange transients determined polarographically. Chlorophyll fluorescence induction was affected by increased hydrostatic pressure in three distinct ways: 1. At 400 atm loss of the first fluorescence drop (I-D transient), reflecting inhibition of PSI activity; 2. at 400 -1200 atm suppression of the fluores­ cence peak (D -P -S transient), indicating a block at the electron donor site of PS II; 3. at 800 -1200 atm flattening of the first fluorescence rise (O -I transient), suggesting a loss of ex­ citation energy within the pigment system. Pressure effects on oxygen exchange include inhibition of transient oxygen uptake and stimulation of the initial oxygen burst, which is paralleled by loss of the first transient fluorescence drop. Inhibition of the second oxygen burst is accompanied by the elimination of the transient fluorescence peak. The first burst only decreases with pressures exceeding 800 atm, as does the initial fluorescence rise. All pressure effects on fluorescence and oxygen exchange were reversible. Hydrostatic pressure appears to be a useful multilateral inhibitor in the study of primary photosynthetic reactions

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