Analysis of electron flow around photosystem II in atrazine-resistant plants applying the three-state energy trapping model on the OIJP fluorescence induction curve

Abstract

Chlorophyll a fluorescence is a very convenient tool to study plant stress. Especially the Fv/Fm ratio has been successfully used. However, the information of Fv/Fm values is limited. Much more information becomes available from the full data of the fluorescence induction curve measured with the Hansatech Plant Efficiency Analyser, the OJIP transient(1). Based on the three-state model (2) for energy trapping and chlorophyll fluorescence in photosystem II a simulation program was developed by Vredenberg et al. (these proceedings). This program was tested using atrazine-resistant plants (3) which have an impairment in the electron flow transport between QA and QB. It was observed that the rate constants of the oxygen evolving complex in S1, S2, S3, S4(0) were about the same in the resistant and the wild-type plants. However, the rate constant of electron flow from QA- to QB was 30% slower in the resistant plants, while the rate constant of electron flow from QA- to QB- in resistant plants was only 3.5% of that in wild-type ones. (1) A Stirbet, Govindjee, B Strasser & RJ Strasser (1998) J Theor Biol 193: 131-151. (2) WJ Vredenberg (2000) Biophys J 79: 26-38. (3) VB Curwiel & JJS van Rensen (1996) J Photochem Photobiol B: Biol 35: 189-195.