Non-Invasive Monitoring of the Light-Induced Cyclic Photosynthetic Electron Flow during Cold Hardening in Wheat Leaves

2006 ◽  
Vol 61 (9-10) ◽  
pp. 734-740 ◽  
Author(s):  
Simona Apostol ◽  
Gabriella Szalai ◽  
László Sujbert ◽  
Losanka P. Popova ◽  
Tibor Janda
Keyword(s):  
Winter Wheat ◽  
Electron Flow ◽  
Wheat Variety ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Light Conditions ◽  
Non Invasive ◽  
Photosynthetic Electron Flow ◽  
Temperature Hardening ◽  
Wheat Leaves

AbstractThe effect of irradiance during low temperature hardening was studied in a winter wheat variety. Ten-day-old winter wheat plants were cold-hardened at 5 °C for 11 days under light (250 μmol m-2 s-1) or dark (20 μmol m-2 s-1) conditions. The effectiveness of hardening was significantly lower in the dark, in spite of a slight decrease in the Fv/Fm chlorophyll fluorescence induction parameter, indicating the occurrence of photoinhibition during the hardening period in the light. Hardening in the light caused a downshift in the far-red induced AG (afterglow) thermoluminescence band. The faster dark re-reduction of P700+, monitored by 820-nm absorbance, could also be observed in these plants. These results suggest that the induction of cyclic photosynthetic electron flow may also contribute to the advantage of frost hardening under light conditions in wheat plants.

A Chloroplast Photosystem 2 Reaction Resistant to Salicylaldoxime

1977 ◽  
Vol 32 (11-12) ◽  
pp. 968-972 ◽  
Author(s):  
G. F. W. Searle
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Electron Acceptor ◽  
Photosystem 2 ◽  
Electron Flow ◽  
Fluorescence Induction ◽  
Initial Slope ◽  
Chlorophyll Fluorescence Induction ◽  
Fluorescence Level ◽  
A Site

Abstract Photoreduction of the artificial electron acceptor, cytochrome c, by isolated spinach chloroplasts in the absence of added catalyst has been found to be resistant to inhibition by 10 mᴍ salicyl­ aldoxime. This contrasts with the pronounced inhibition of the photoreduction of both 2,6-dichloro-phenolindophenol and ferricyanide over a range of electron flow rates, and indicates an inhibition on the acceptor side rather than on the donor side of photosystem 2 (PS2). All photoreductions were susceptible to inhibition by 3-(3′,4′-dichlorophenyl)-1, 1-dimethyl urea (DCMU). Salicyl­ aldoxime (1 -10 mᴍ) inhibited electron flow from PS2 to P700, and also altered the chlorophyll fluorescence induction of dark-adapted chloroplasts. Salicylaldoxime concentrations up to 5 mM did not change the initial fluorescence level, F0 , or the initial slope, (dF/dt)0 , but lowered the final steady state fluorescence level, Fm , and the value of p0 [p0= (Fm - F0)/Fm] ; an effect similar to that seen on 1 mᴍ ferricyanide addition, thus indicating an induced oxidation of the fluorescence quencher, Q. Both DCMU and orthophenanthroline, which block electron transport directly after Q, caused an increase in (dF/dt)0 , F0 and Fm but left p0 unchanged. This contrasted with the effect of salicylaldoxime. It is proposed that salicylaldoxime inhibits electron transport from PS2 to photosystem 1, at a site which can probably be identified with the plastoquinone pool, by inducing a cyclic flow of electrons around PS2. Cytochrome c, under the conditions used, appears to be photoreduced at a site close to the secondary electron acceptor, R, of PS2.

scholarly journals Photosynthesis acclimation under severely fluctuating light conditions allows faster growth of diatoms compared with dinoflagellates

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lu Zhou ◽  
Songcui Wu ◽  
Wenhui Gu ◽  
Lijun Wang ◽  
Jing Wang ◽  
...  
Keyword(s):  
Red Tide ◽  
Skeletonema Costatum ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Specific Inhibitor ◽  
Dynamic Environments ◽  
Thalassiosira Pseudonana ◽  
Light Conditions ◽  
Photosynthetic Electron Flow ◽  
Fluctuating Light

Abstract Background Diatoms contribute 20% of the global primary production and are adaptable in dynamic environments. Diatoms always bloom earlier in the annual phytoplankton succession instead of dinoflagellates. However, how diatoms acclimate to a dynamic environment, especially under changing light conditions, remains unclear. Results We compared the growth and photosynthesis under fluctuating light conditions of red tide diatom Skeletonema costatum, red tide dinoflagellate Amphidinium carterae, Prorocentrum donghaiense, Karenia mikimotoi, model diatom Phaeodactylum tricornutum, Thalassiosira pseudonana and model dinoflagellate Dinophycae Symbiodinium. Diatoms grew faster and maintained a consistently higher level of photosynthesis. Diatoms were sensitive to the specific inhibitor of Proton Gradient Regulation 5 (PGR5) depending photosynthetic electron flow, which is a crucial mechanism to protect their photosynthetic apparatus under fluctuating light. In contrast, the dinoflagellates were not sensitive to this inhibitor. Therefore, we investigate how PGR5 functions under light fluctuations in the model diatom P. tricornutum by knocking down and overexpressing PGR5. Overexpression of PGR5 reduced the photosystem I acceptor side limitation (Y (NA)) and increased growth rate under severely fluctuating light in contrast to the knockdown of PGR5. Conclusion Diatoms acclimatize to fluctuating light conditions better than dinoflagellates. PGR5 in diatoms can regulate their photosynthetic electron flow and accelerate their growth under severe light fluctuation, supporting fast biomass accumulation under dynamic environments in pioneer blooms.

Chlorophyll fluorescence as a rapid test for reaction to urea herbicides in winter wheat

1988 ◽  
Vol 110 (3) ◽  
pp. 627-632 ◽  
Author(s):  
Margaret Harris ◽  
M. S. Camlin
Keyword(s):  
Triticum Aestivum ◽  
Chlorophyll Fluorescence ◽  
Winter Wheat ◽  
Screening Method ◽  
Rapid Test ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Effective Screening ◽  
And Control

SummaryA simple and rapid test is described which can be used to determine tolerance to metoxuron and chlortoluron herbicides in winter wheat (Triticum aestivumL.) cultivars. Seedlings 5 days old were treated by root application of herbicide for 24 h and tolerant and susceptible cultivars were identified by comparing the chlorophyll fluorescence induction curves for both herbicide-treated and control plants after 7 days. The method was thus capable of detecting cultivar tolerance or susceptibility to the herbicides within 12 days of sowing the seed, providing a rapid and effective screening method. Possible uses for this new test are discussed.

Rate of Photosynthesis and Transpiration of Winter Wheat Leaves and Ears Under Water Deficit Conditions

2008 ◽  
Vol 23 (2) ◽  
pp. 326-335
Author(s):  
Jacek Olszewski ◽  
Agnieszka Pszczółkowska ◽  
Tomasz Kulik ◽  
Gabriel Fordoński ◽  
Krystyna Płodzień ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Water Deficit ◽  
Rate Of Photosynthesis ◽  
Wheat Leaves

Winter Wheat Variety Test

2007 ◽  
Author(s):  
Ronald Skrdla ◽  
Jean-Luc Jannink
Keyword(s):  
Winter Wheat ◽  
Wheat Variety ◽  
Winter Wheat Variety

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Fluorescence as a tool in photosynthesis research: application in studies of photoinhibition, cold acclimation and freezing stress

1989 ◽  
Vol 323 (1216) ◽  
pp. 281-293 ◽  
Keyword(s):  
Quantum Yield ◽  
Cold Acclimation ◽  
Spinacia Oleracea ◽  
Photosynthetic Apparatus ◽  
Fluorescence Induction ◽  
High Light ◽  
Thermal Dissipation ◽  
Freezing Stress ◽  
Chlorophyll Fluorescence Induction ◽  
Freezing And Thawing

Chlorophyll fluorescence induction (at 20 °C and 77 K) and quenching were analysed in relation to effects of environmental stresses imposed by chilling in high light and by freezing and thawing of spinach ( Spinacia oleracea L.) leaves. The data indicate that cold acclimation of spinach plants, which leads to increased frost tolerance of the leaves, results in decreased susceptibility to photoinhibition of photosynthesis at chilling temperatures. When plants acclimated to 18 °C and 260-300 µmol quanta m -2 s -1 were exposed to higher light (550 µmol quanta m -2 s -1 ) at 4 °C, they developed strong photoinhibition, as characterized by decreased quantum yield of O 2 evolution and decreased ratio of variable: maximum fluorescence (F V /F M ) of photosystem II. The decrease in F V /F M resulted from a decline in F V and an increase in F 0 . The F V /F M ratio was lowered to a significantly greater extent when induction was recorded at 20 °C, as compared with 77 K. The effects related to photoinhibition were fully reversible at 18 °C in dim light. Plants that had been cold-acclimated for 10 days exhibited slightly decreased quantum yield and lowered F V /F M ratio. However, they did not show further photoinhibition on exposure to 550 µmol quanta m -2 s -1 at 4 °C. The reversible photoinhibition is discussed as a protective pathway serving for thermal dissipation of excessive light energy. It is hypothesized that such a mechanism prevents destruction of the photosynthetic apparatus, until other means of protection become effective during long-term acclimation to high light. Inhibition of photosynthetic carbon assimilation caused by freezing and thawing of leaves in the dark was closely correlated with inhibition of photochemical fluorescence quenching (q Q ). As a sensitive response of the thylakoid membranes to freezing stress, the energy-dependent quenching, q E , was inhibited. Only more severe impact of freezing caused a significant decline in the F V /F M ratio. It is concluded that measurements of fluorescence induction signals ( F V /F M ratios) provide a sensitive tool with which to investigate photoinhibition, whereas freezing damage to the photosynthetic system can be detected more readily by the quenching coefficients q Q and q E than by F V /F M ratios.

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