Probing the photosynthetic apparatus noninvasively in the laboratory of Reto Strasser in the countryside of Geneva between 2001 and 2009

An overview is given of several studies on the fast chlorophyll (Chl) a fluorescence (OJIP) transient carried out in the laboratory of Reto Strasser between 2001 and 2009. At the beginning of this period the HandyPEA and PEA-Senior instruments were introduced by Reto Strasser and Hansatech Instruments Ltd. (UK) that gave a lot of experimental flexibility compared to the experiments that were feasible in the preceding years. These technical innovations, including the combination of 820-nm transmission measurements (for the determination of the P-700 and PC redox states) and Chl a fluorescence [originating from photosystem II (PSII)], enabled us to establish the effects of electron flow through and at the acceptor side of photosystem I during a dark-to-light transition on fluorescence induction in leaves. These instruments further allowed us to show biological variability between various photosynthetic organisms and how several chemical treatments could modify the Chl a fluorescence kinetics. We also obtained new information on the effect of the inhibitor DCMU [3-(3',4'-dichlorophenyl)-1,1-dimethylurea] on Chl a fluorescence induction. In addition, the effects of heat stress on electron flow through PSII and the entire electron transport chain were investigated in detail. The article also reflects how our perception and interpretation of the OJIP kinetics changed over time.