In vivo Changes in Chloroplast ThylakoidMembrane Activity during Viable and Non-viable Dehydration of a Drought-tolerant Plant, Borya nitida

1982 ◽  
Vol 9 (5) ◽  
pp. 611 ◽  
Author(s):  
SE Hethzerington ◽  
RM Smillie ◽  
ND Hallam
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Fluorescence Induction ◽  
Cytochrome F ◽  
Chlorophyll Fluorescence Induction ◽  
Reaction Centre ◽  
Partial Recovery ◽  
Induction Kinetics ◽  
Slow Development

Expanded leaves of Borya nitida Labill. were detached and placed in atmospheres of 100, 96, 88, 53 or 13% relative humidity at 25°C. In vivo chlorophyll fluorescence induction kinetics and the photooxidation of cytochrome f were measured before and after dehydration and again after rehydration by floating on water. In contrast to slow dehydration at 96% R.H., which resulted in an initial stimulation of photosystem II activity, the slow development of a partial block on the photoreducing side of photosystem II and the eventual degreening of leaves to a yellow viable condition, fast dehydration at 13% R.H. induced rapid loss of photosystem I activity and a slower development of a block on the photooxidizing side of photosystem . Although the leaves remained green, photo- system activity did not recover upon rehydration. Charge separation in the photosystem II complex still took place in the dehydrated leaves but upon rehydration the photosystem II reaction centre appeared to be disassociated from the light harvesting system. Dehydration at intermediate relative humidities (88 and 53%) led to a partial block on the photoreducing side of photosystem II and, more slowly, inhibition of photosynthetic electron transfer on the photooxidizing side of photosystem II. Following rehydration there was partial recovery of reactions associated with photosystem I but the leaves were unable to return to their original condition.

Humidity-sensitive Degreening and Regreening of Leaves of Borya nitida Labill. As Followed by Changes in Chlorophyll Fluorescence

1982 ◽  
Vol 9 (5) ◽  
pp. 587 ◽  
Author(s):  
SE Hethzerington ◽  
RM Smillie
Keyword(s):  
Chlorophyll Fluorescence ◽  
Relative Humidity ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Fluorescence Induction ◽  
Physiological Age ◽  
Chlorophyll Fluorescence Induction ◽  
Induction Kinetics ◽  
Mediated Electron Transfer

Fast and slow chlorophyll fluorescence induction kinetics were used to follow changes in photosynthetic activity during humidity-sensitive degreening and regreening of leaves of Borya nidita Labill. During dry periods the leaves of this desiccation-tolerant plant lose chlorophyll, becoming yellow-brown and upon rehydration turn green again. This degreening process can be simulated in detached leaves by slow dehydration at 96% relative humidity. Under these conditions changes in chlorophyll fluorescence in vivo and the activities of photosystems I and II in chloroplasts isolated from dehydrated leaves indicated that degreening was accompanied initially by a stimulation of photosystem II activity and a gradual decrease in photosystem I-mediated electron transfer, while at advanced stages of degreening both photosystems were lost. Control leaves detached and kept at 100% relative humidity remained green and showed little change in chlorophyll fluorescence kinetics. During the rehydration and subsequent regreening of dry yellow leaves, photosystem I activity appeared to recover faster than photosystem II. The ability of the leaves to recover and regreen from the dried state, either on the plant or after detachment, depended upon the physiological age of the leaves at the time of dehydration.

Effects of Pyridazinone Herbicides during Chloroplast Development in Detached Barley Leaves III. Effects of SAN 6706 on Photosynthetic Activity and Chlorophyll-Protein Complexes

1986 ◽  
Vol 41 (5-6) ◽  
pp. 585-590 ◽  
Author(s):  
G. Laskay ◽  
E. Lehoczki ◽  
A. L. Dobi ◽  
L. Szalay
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Protein Complexes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Fluorescence Induction ◽  
Hill Reaction ◽  
Practical Reasons ◽  
Barley Leaves

The photosynthetic activities of barley leaves in vivo and of thylakoids, isolated from the leaves, in vitro were studied during greening in the presence or absence of 2 × 10-4 м SAN 6706. The degree of chlorophyll bleaching increased from 32% at 24 h of greening to 60% at the final stage. Treated leaves were unable to carry out 14CO2-fixation, their fluorescence induction properties showed very limited, if any, photosystem II-activity, and the thylakoids isolated from the leaves were also inactive in mediating ferricyanide Hill reaction. The leaves, however, exhibited lightinduced quenching of fluorescence revealed by slow fluorescence induction measurements; and the thylakoids were active in mediating photosystem I-specific in vitro Mehler reaction. Thylakoid membranes of the chloroplasts isolated from treated leaves contained CP 1 and LHCP3 bands as revealed by polyacrylamide gel electrophoresis. From these results it is concluded that i) greening in the presence of SAN 6706 leads to the formation of inactive photosystem -II units; that ii) photosystem-I per se is active in vitro, and can, possibly, mediate cyclic electron transport in vivo coupled to the formation of ATP; and that iii) the presence of xanthophyll pigments is required for the assembly of the light-harvesting complex.The experiments were repeated with the application of SAN 9789, another pyridazinone compound, and yielded practically the same results as those obtained with SAN 6706. For practical reasons, only the results obtained with SAN 6706 are demonstrated throughout this communication.

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.

Fluorescence Induction From Photosystem II: Analytical Equations for the Yields of Photochemistry and Fluorescence Derived From Analysis of a Model Including Exciton-Radical Pair Equilibrium and Restricted Energy Transfer Between Photosynthetic Units

1995 ◽  
Vol 22 (2) ◽  
pp. 183 ◽  
Author(s):  
HW Trissl ◽  
J Lavergne
Keyword(s):  
Photosystem Ii ◽  
Radical Pair ◽  
Fluorescence Induction ◽  
Reaction Centre ◽  
Continuous Transition ◽  
Reaction Centres ◽  
Induction Kinetics ◽  
Lake Model ◽  
Time Courses ◽  
Analytical Relations

The theoretical relationships between the fluorescence and photochemical yields of photosystem II (PSII) and the fraction of open reaction centres are examined in a model based on the following assumptions: (a) a homogeneous, infinite PSII domain; (b) exciton-radical pair equilibrium; and (c) different rates of exciton transfer between 'core' and 'peripheral' antenna beds. Simple analytical relations are examined for the yields and their time-courses in induction experiments. Variation of the inter-unit transfer rate allows continuous transition from the case of 'separated units' to the pure 'lake' model. Widely used relations for estimating the fraction of closed reaction centres from the complementary area of the fluorescence, or the photochemical yield from fluorescence levels are derived. An experimental induction curve is analysed, considering its composition of 'α' and 'β' centres. The sigmoidicity of the induction kinetics is characterised by a single parameter J (corresponding to Joliots' 'p'), that is shown to depend on both the connectivity of the photosynthetic units and on reaction centre parameters. On the other hand, the relation between J and the extreme fluorescence levels (or the deviation from the linear Stern-Volmer dependence of 1 /Φf, on the fraction of open traps) is only controlled by antenna connectivity. Experimental data are more consistent with a model of 'connected units' for PSIIα than with the pure 'lake' model.

Drought resistance of hard wheat cultivars measured by a rapid chlorophyll fluorescence test

1985 ◽  
Vol 104 (3) ◽  
pp. 501-504 ◽  
Author(s):  
M. Havaux ◽  
R. Lannoye
Keyword(s):  
Chlorophyll Fluorescence ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Quenching Rate ◽  
Simple Method ◽  
Hard Wheat ◽  
Drought Tolerant ◽  
Resistant Varieties ◽  
Slow Fluorescence Induction

SummaryDisks of hard wheat (Triticum durum Desf.) leaves subjected to rapid desiccation over 4 h showed noticeable changes in the shape of the in vivo chlorophyll fluorescence induction curves. In drought-sensitive varieties (such as Claridoc), water stress resulted in a strong inhibition of the slow fluorescence induction transients. In particular, the fluorescence quenching rate was markedly decreased in water-stressed leaf disks. In contrast, leaves of drought-resistant varieties (such as Aouedj) showed only minor changes in chlorophyll fluorescence. The results of this investigation suggest that the slow transient of the in vivo chlorophyll fluorescence induction phenomenon may provide a simple method for selecting drought-tolerant wheats.

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