title: Comparison of thylakoid structure and organization in sun and shade Haberlea rhodopensis populations under desiccation and rehydration.
abstract: The resurrection plant, Haberlea rhodopensis can survive nearly total desiccation only in its usual low irradiation environment. However, populations with similar capacity to recover were discovered recently in several sunny habitats. To reveal what kind of morphological, structural and thylakoid-level alterations play a role in the acclimation of this low-light adapted species to high-light environment and how do they contribute to the desiccation tolerance mechanisms, the structure of the photosynthetic apparatus, the most sensitive component of the chlorophyll-retaining resurrection plants, was analyzed by transmission electron microscopy, steady state low-temperature fluorescence and two-dimensional Blue-Native/SDS PAGE under desiccation and rehydration. In contrast to the great differences in the morphology of plants, the ultrastructure and the organization of thylakoids were surprisingly similar in well-hydrated shade and sun populations. A high ratio of photosystem (PS)I binding light harvesting complex (LHC)II, important in low- and fluctuating light environment, was characteristic to both shade and sun plant, and the ratios of the main chlorophyll-protein complexes were also similar. The intensive protective mechanisms, such as shading by steep leaf angle and accumulation of protective substances, probably reduced the light intensity at the chloroplast level. The significantly increased ratio of monomer to oligomer antennae in well-hydrated sun plants may be connected with the temporary high light exposure of chloroplasts. During desiccation, LHCII was removed from PSI and part of PSII supercomplexes disassembled with some loss of PSII core and LHCII. The different reorganization of antennae, possibly connected with different quenching mechanisms, involved an increased amount of monomers in shade plants but unchanged proportion of oligomers in sun plants. Desiccation-induced responses were more pronounced in sun plants which also had a greater capacity to recover due to their stress-acclimated attitude.
authors.affiliation: Department of Plant Physiology and Molecular Plant Biology, Institute of Biology, Eötvös Loránd University, Pázmány P. sétány 1/C, H-1117 Budapest, Hungary. Electronic address: eva.sarvari@ttk.elte.hu.
authors.forename: Eva
authors.initials: E
authors.lastname: Sárvári
authors.affiliation: Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Bl. 21, BG-1113 Sofia, Bulgaria. Electronic address: gkm_rw@abv.bg.
authors.forename: Gergana
authors.initials: G
authors.lastname: Mihailova
authors.affiliation: Department of Plant Physiology and Molecular Plant Biology, Institute of Biology, Eötvös Loránd University, Pázmány P. sétány 1/C, H-1117 Budapest, Hungary. Electronic address: adam.solti@ttk.elte.hu.
authors.forename: Adám
authors.initials: A
authors.lastname: Solti
authors.affiliation: Department of Plant Anatomy, Institute of Biology, Eötvös Loránd University, Pázmány P. sétány 1/C, H-1117 Budapest, Hungary. Electronic address: aron.keresztes@ttk.elte.hu.
authors.forename: Aron
authors.initials: A
authors.lastname: Keresztes
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Bl. 21, BG-1113 Sofia, Bulgaria. Electronic address: mayav@bio21.bas.bg.
authors.forename: Maya
authors.initials: M
authors.lastname: Velitchkova
authors.affiliation: Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Bl. 21, BG-1113 Sofia, Bulgaria. Electronic address: katya@bio21.bas.bg.
authors.forename: Katya
authors.initials: K
authors.lastname: Georgieva
mesh_terms: D061146:Chlorophyll Binding Proteins / Q000378:metabolism; D002736:Chloroplasts / Q000528:radiation effects / Q000648:ultrastructure; D003624:Darkness; D003890:Desiccation; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D019684:Magnoliopsida / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D010940:Plant Proteins / Q000378:metabolism; D040901:Proteomics; D013050:Spectrometry, Fluorescence; D020524:Thylakoids / Q000528:radiation effects / Q000648:ultrastructure*; D014867:Water
chemical_list: D061146:Chlorophyll Binding Proteins; D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D014867:Water
keywords: Blue-Native PAGE; Chlorophyll–protein complexes; Electron microscopy; Resurrection plant; Steady-state 77K fluorescence