The Steady State Chlorophyll a Fluorescence Exhibits in Vivo an Optimum as a Function of Light Intensity which Reflects the Physiological State of the Plant : MEMBRANES AND BIOENERGETICS

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概要

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• Modulated (690 and 730 nm), as well as direct chlorophyll (Chl) a fluorescence and changes in the concentration of the oxidized P700 were measured under steady state conditions in leaves of higher plants adapted to different light intensities. All the leaf samples exhibit an optimum curve of steady state fluorescence yield (F_s) versus the light intensity but its position with respect to light intensity varies considerably from one species to another or from one sample to other even in the same plant or within the same leaf sample. However, the optimum level of F_s was always at a moderate light intensity. By using the modulated fluorescence technique, the system with all closed (F^1_m) or open reaction center (F^1_o) were measured in steady state conditions. Each experimentally measured fluorescence yield was separated into a fluorescence emission of open (F_<open< = F^1_o・(1-V_s)) and closed (F_<closed< = (F^1_m・V_s)) reaction center (RC) of photosystem II where V_s = (F_s-F^1_o)/(F^1_m-F^1_o) is the function of fraction of closed reaction centers. With increasing light intensity, the fraction of open RC decreased while the fraction of closed RC increased. Maximum quantum efficiency (ΦP_o) and actual quantum efficiency (ΦP) decreased by increasing light intensity. An optimum level of F_s was observed, when the fraction of closed reaction centers V_s of each sample was about 0.2 showing a common quenching mechanism which determines the fluorescence properties under steady state condition. This explains the apparent phenomenological contradiction that the fluorescence yield under steady state conditions can increase or decrease upon an increase of actinic light.

• 日本植物生理学会の論文

著者

• Strasser Reto

  Bioenergetics Laboratory University Of Geneva

• Srivastava Alaka

  Bioenergetics Laboratory, University of Geneva

• Greppin H.

  Laboratory of Plant Physiology and Biochemistry

• Greppin H.

  Laboratoire De Physiologie Vegetale

• Srivastava Alaka

  Bioenergetics Laboratory University Of Geneva

関連論文

• The Steady State Chlorophyll a Fluorescence Exhibits in Vivo an Optimum as a Function of Light Intensity which Reflects the Physiological State of the Plant : MEMBRANES AND BIOENERGETICS
• Evolution de l'activite auxines-oxydasique et peroxydasique lors de l'induction photoperiodique et de la sexualisation de l'epinard

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