In intact leaves, the maximum fluorescence level (FM) is independent of the redox state of the plastoquinone pool: A DCMU-inhibition study

Szilvia Z. Tóth, G. Schansker, Reto J. Strasser

Research output: Contribution to journalArticle

93 Citations (Scopus)

Abstract

The effects of DCMU (3-(3′,4′-dichlorophenyl)-1,1-dimethylurea) on the fluorescence induction transient (OJIP) in higher plants were re-investigated. We found that the initial (F0) and maximum (F M) fluorescence levels of DCMU-treated leaves do not change relative to controls when the treatment is done in complete darkness and DCMU is allowed to diffuse slowly into the leaves either by submersion or by application via the stem. Simultaneous 820 nm transmission measurements (a measure of electron flow through Photosystem I) showed that in the DCMU-treated samples, the plastoquinone pool remained oxidized during the light pulses whereas in uninhibited leaves, the FM level coincided with a fully reduced electron transport chain. The identical FM values with and without DCMU indicate that in intact leaves, the FM value is independent of the redox state of the plastoquinone pool. We also show that (i) the generally observed F0 increase is probably due to the presence of (even very weak) light during the DCMU treatment, (ii) vacuum infiltration of leaf discs leads to a drastic decrease of the fluorescence yield, and in DCMU-treated samples, the FM decreases to the I-level of their control (leaves vacuum infiltrated with 1% ethanol), (iii) and in thylakoid membranes, the addition of DCMU lowers the FM relative to that of a control sample.

Original languageEnglish
Pages (from-to)275-282
Number of pages8
JournalBBA - Bioenergetics
Volume1708
Issue number2
DOIs
Publication statusPublished - Jun 30 2005

Fingerprint

Plastoquinone
Diuron
Oxidation-Reduction
Fluorescence
Vacuum
Photosystem I Protein Complex
Light
Thylakoids
Darkness
Immersion
Electron Transport
Infiltration
Ethanol
Electrons
Membranes

Keywords

  • 820 nm transmission
  • Chlorophyll a fluorescence
  • DCMU
  • OJIP transient
  • Plastoquinone pool quenching

ASJC Scopus subject areas

  • Biophysics

Cite this

In intact leaves, the maximum fluorescence level (FM) is independent of the redox state of the plastoquinone pool : A DCMU-inhibition study. / Tóth, Szilvia Z.; Schansker, G.; Strasser, Reto J.

In: BBA - Bioenergetics, Vol. 1708, No. 2, 30.06.2005, p. 275-282.

Research output: Contribution to journalArticle

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