Chloroplast Cytochrome b6/f and ATP Synthase Complexes in Tobacco: Transformation With Antisense RNA Against Nuclear-Encoded Transcripts for the Rieske FeS and ATPδ Polypeptides

1995 ◽  
Vol 22 (2) ◽  
pp. 285 ◽  
Author(s):  
GD Price ◽  
JW Yu ◽  
SV Caemmerer ◽  
JR Evans ◽  
WS Chow ◽  
...  
Keyword(s):  
Steady State ◽  
Atp Synthase ◽  
Antisense Rna ◽  
Photochemical Quenching ◽  
Cdna Clones ◽  
Wild Type ◽  
Cytochrome B6 ◽  
Steady State Fluorescence ◽  
Fluorescence Measurements ◽  
Non Photochemical Quenching

Tobacco plants with reduced amounts and activities of both the chloroplast cytochrome b6/f and ATP synthase complexes have been produced using antisense RNA techniques. Antisense constructs were generated from tobacco cDNA clones coding for the Rieske FeS protein and the δ subunit of the b6/f and ATP synthase complexes respectively. Transformants with altered activities were selected using pulse-modulated fluorescence measurements. The b6/ftransformants showed high levels of steady-state fluorescence and reduced levels of both photochemical and non-photochemical quenching. In striking contrast, the ATP synthase transformants showed low levels of steady-state fluorescence and greatly increased levels of non-photochemical quenching. Transformants with a range of suppression were isolated for both constructs, in some cases with photosynthesis reduced to less than 10% of wild-type values. The most severely affected transformants showed extremely slow growth and in some cases they were unable to grow and produce seed. Progeny from the R1 seed from several cytochrome b6/f transformants have been analysed and show segregation of phenotypes ranging from intermediate to severe in repression. Intermediate and severe phenotype plants showed a reduction in Rieske FeS mRNA of more than 90% while FeS polypeptide was reduced to 60 and 86% of wild type. There was a strong correlation between photosynthesis at air and Rieske FeS polypeptide content in the antisense plants suggesting that the cytochrome b6/f complex was a major determinant of photosynthetic rate under these conditions. Photoinhibition studies of FeS antisense plants showed that there was a reduced activity of the xanthophyll cycle in the most severe plants, consistent with a reduction in the transthylakoid pH gradient and a lowered non-photochemical quenching. Preliminary studies of the ATPδ antisense plants showed that they also had reduced levels of mRNA and ATPδ polypeptide.

Light Absorption and Partitioning in Response to Nitrogen in Apple Leaves

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541a-541
Author(s):  
Lailiang Cheng ◽  
Leslie H. Fuchigami ◽  
Patrick J. Breen
Keyword(s):  
High Light ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Light Conditions ◽  
Psii Efficiency ◽  
Fluorescence Measurements ◽  
Free Radical Formation ◽  
Highly Correlated ◽  
Non Photochemical Quenching ◽  
Leaf N

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.

An Arabidopsis thaliana mutant, altered in the γ-subunit of ATP synthase, has a different pattern of intensity-dependent changes in non-photochemical quenching and kinetics of the P-to-S fluorescence decay

2002 ◽  
Vol 29 (4) ◽  
pp. 425 ◽  
Author(s):  
Govindjee ◽  
Paul Spilotro
Keyword(s):  
Arabidopsis Thaliana ◽  
Xanthophyll Cycle ◽  
Fluorescence Decay ◽  
Coupling Factor ◽  
Photochemical Quenching ◽  
Wild Type ◽  
Marked Rise ◽  
Chl A ◽  
Chl A Fluorescence ◽  
Non Photochemical Quenching

A major photoprotective mechanism that plants employ against excess light involves interplay between the xanthophyll cycle and the accumulation of protons. Using mutants in the xanthophyll cycle, the roles of violaxanthin, antheraxanthin and zeaxanthin have already been well established. In this paper, we present data on intact leaves of a mutant [coupling factor quick recovery mutant (cfq); atpC1:E244K] of Arabidopsis thaliana that we expected, based on 515-nm absorbance changes (Gabrys et al. 1994, Plant Physiology 104, 769–776), to have differences in light-induced ΔpH. The significance of this paper is: (i) it is the first study of the photoprotective energy dissipation involving a mutant of the pH gradient; it establishes that protons play an important role in the pattern of non-photochemical quenching (NPQ) of chlorophyll (Chl) a fluorescence; and (ii) differences between the cfq and the wild type (wt) are observed only under subsaturating light intensities, and are strongest in the initial few minutes of the induction period. Our results on light-intensity dependent Chl* a fluorescence transients (the Kautsky effect), and on NPQ of Chl a fluorescence, at 50–250 μmol photons m–2 s–1 demonstrate: (i) the ‘P-to-S’ (or ‘T’) decay, known to be related to [H+] (Briantais et al. 1979, Biochimica et Biophysica Acta 548, 128–138), is slowed in the mutant; and (ii) the pattern of NPQ kinetics is different in the initial 100 s — in the wt leaves, there is a marked rise and decline, and in the cfq mutant, there is a slowed rise. These differences are absent at 750 μmol photons m–2 s–1. Pre-illumination and nigericin (an uncoupler that dissipates the proton gradient) treatment of the cfq mutant, which has lower ΔpH relative to wild type, confirm the conclusion that protons play an important role in the quenching of Chl a fluorescence.

Ultrafast transient-absorption and steady-state fluorescence measurements on 2-aminopurine substituted dinucleotides and 2-aminopurine substituted DNA duplexes

2004 ◽  
Vol 6 (1) ◽  
pp. 154 ◽  
Author(s):  
Olaf F. A. Larsen ◽  
Ivo H. M. van Stokkum ◽  
Frank L. de Weerd ◽  
Mikas Vengris ◽  
Charuvila T. Aravindakumar ◽  
...  
Keyword(s):  
Steady State ◽  
Transient Absorption ◽  
Dna Duplexes ◽  
Steady State Fluorescence ◽  
Fluorescence Measurements ◽  
Ultrafast Transient Absorption

Dynamic quenching in single photosystem II supercomplexes

2016 ◽  
Vol 18 (37) ◽  
pp. 25852-25860 ◽  
Author(s):  
J. Michael Gruber ◽  
Pengqi Xu ◽  
Jevgenij Chmeliov ◽  
Tjaart P. J. Krüger ◽  
Maxime T. A. Alexandre ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photochemical Quenching ◽  
Dynamic Quenching ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Fluorescence Measurements ◽  
Non Photochemical Quenching

Time-resolved fluorescence measurements of single PSII supercomplexes to investigate blinking and dynamic quenching in the context of non-photochemical quenching (NPQ).

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