title: Photoprotection conferred by changes in photosynthetic protein levels and organization during dehydration of a homoiochlorophyllous resurrection plant.
abstract: During desiccation, homoiochlorophyllous resurrection plants retain most of their photosynthetic apparatus, allowing them to resume photosynthetic activity quickly upon water availability. These plants rely on various mechanisms to prevent the formation of reactive oxygen species and/or protect their tissues from the damage they inflict. In this work, we addressed the issue of how homoiochlorophyllous resurrection plants deal with the problem of excessive excitation/electron pressures during dehydration using Craterostigma pumilum as a model plant. To investigate the alterations in the supramolecular organization of photosynthetic protein complexes, we examined cryoimmobilized, freeze-fractured leaf tissues using (cryo)scanning electron microscopy. These examinations revealed rearrangements of photosystem II (PSII) complexes, including a lowered density during moderate dehydration, consistent with a lower level of PSII proteins, as shown by biochemical analyses. The latter also showed a considerable decrease in the level of cytochrome f early during dehydration, suggesting that initial regulation of the inhibition of electron transport is achieved via the cytochrome b6f complex. Upon further dehydration, PSII complexes are observed to arrange into rows and semicrystalline arrays, which correlates with the significant accumulation of sucrose and the appearance of inverted hexagonal lipid phases within the membranes. As opposed to PSII and cytochrome f, the light-harvesting antenna complexes of PSII remain stable throughout the course of dehydration. Altogether, these results, along with photosynthetic activity measurements, suggest that the protection of retained photosynthetic components is achieved, at least in part, via the structural rearrangements of PSII and (likely) light-harvesting antenna complexes into a photochemically quenched state.
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Dana
authors.initials: D
authors.lastname: Charuvi
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Reinat
authors.initials: R
authors.lastname: Nevo
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Eyal
authors.initials: E
authors.lastname: Shimoni
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Leah
authors.initials: L
authors.lastname: Naveh
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Ahmad
authors.initials: A
authors.lastname: Zia
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Zach
authors.initials: Z
authors.lastname: Adam
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Jill M
authors.initials: JM
authors.lastname: Farrant
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.).
authors.forename: Helmut
authors.initials: H
authors.lastname: Kirchhoff
authors.affiliation: Department of Biological Chemistry (D.C., R.N., Z.R.) and Electron Microscopy Unit (E.S.), Weizmann Institute of Science, Rehovot 76100, Israel;Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel (L.N., Z.A.);Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (A.Z., H.K.); andDepartment of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa (J.M.F.) ziv.reich@weizmann.ac.il.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Reich
mesh_terms: D032181:Craterostigma / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D045346:Cytochrome b6f Complex / Q000235:genetics / Q000378:metabolism; D003681:Dehydration; D003890:Desiccation; D004579:Electron Transport; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014867:Water / Q000502:physiology
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D014867:Water; D045346:Cytochrome b6f Complex