title: Visualizing heterogeneity of photosynthetic properties of plant leaves with two-photon fluorescence lifetime imaging microscopy.
abstract: Two-photon fluorescence lifetime imaging microscopy (FLIM) was used to analyse the distribution and properties of Photosystem I (PSI) and Photosystem II (PSII) in palisade and spongy chloroplasts of leaves from the C3 plant Arabidopsis thaliana and the C4 plant Miscanthus x giganteus. This was achieved by separating the time-resolved fluorescence of PSI and PSII in the leaf. It is found that the PSII antenna size is larger on the abaxial side of A. thaliana leaves, presumably because chloroplasts in the spongy mesophyll are "shaded" by the palisade cells. The number of chlorophylls in PSI on the adaxial side of the A. thaliana leaf is slightly higher. The C4 plant M. x giganteus contains both mesophyll and bundle sheath cells, which have a different PSI/PSII ratio. It is shown that the time-resolved fluorescence of bundle sheath and mesophyll cells can be analysed separately. The relative number of chlorophylls, which belong to PSI (as compared to PSII) in the bundle sheath cells is at least 2.5 times higher than in mesophyll cells. FLIM is thus demonstrated to be a useful technique to study the PSI/PSII ratio and PSII antenna size in well-defined regions of plant leaves without having to isolate pigment-protein complexes.
authors.affiliation: Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands; BioSolar Cells Project Office, P.O. Box 98, 6700 AB Wageningen, The Netherlands.
authors.forename: Ievgeniia
authors.initials: I
authors.lastname: Iermak
authors.affiliation: Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands.
authors.forename: Jochem
authors.initials: J
authors.lastname: Vink
authors.affiliation: Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands; MicroSpectroscopy Centre, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands.
authors.forename: Arjen N
authors.initials: AN
authors.lastname: Bader
authors.affiliation: Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands.
authors.forename: Emilie
authors.initials: E
authors.lastname: Wientjes
authors.affiliation: Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands; BioSolar Cells Project Office, P.O. Box 98, 6700 AB Wageningen, The Netherlands; MicroSpectroscopy Centre, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands.
authors.forename: Herbert
authors.initials: H
authors.lastname: van Amerongen
mesh_terms: D008856:Microscopy, Fluorescence; D017785:Photons; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex
keywords: Microscopy; Photosynthesis; Photosystem I; Photosystem II; Time-resolved fluorescence