title: Dark-chilling induces substantial structural changes and modifies galactolipid and carotenoid composition during chloroplast biogenesis in cucumber (Cucumis sativus L.) cotyledons.
abstract: Plants in a temperate climate are often subject to different environmental factors, chilling stress among them, which influence the growth especially during early stages of plant development. Chloroplasts are one of the first organelles affected by the chilling stress. Therefore the proper biogenesis of chloroplasts in early stages of plant growth is crucial for undertaking the photosynthetic activity. In this paper, the analysis of the cotyledon chloroplast biogenesis at different levels of plastid organization was performed in cucumber, one of the most popular chilling sensitive crops. Influence of low temperature on the ultrastructure was manifested by partial recrystallization of the prolamellar body, the formation of elongated grana thylakoids and a change of the prolamellar body structure from the compacted "closed" type to a more loose "open" type. Structural changes are strongly correlated with galactolipid and carotenoid content. Substantial changes in the galactolipid and the carotenoid composition in dark-chilled plants, especially a decrease of the monogalactosyldiacylglycerol to digalactosyldiacylglycerol ratio (MGDG/DGDG) and an increased level of lutein, responsible for a decrease in membrane fluidity, were registered together with a slower adaptation to higher light intensity and an increased level of non-photochemical reactions. Changes in the grana thylakoid fluidity, of their structure and photosynthetic efficiency in developing chloroplasts of dark-chilled plants, without significant changes in the PSI/PSII ratio, could distort the balance of photosystem rearrangements and be one of the reasons of cucumber sensitivity to chilling.
authors.affiliation: Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Skupień
authors.affiliation: Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Wójtowicz
authors.affiliation: Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Łucja
authors.initials: Ł
authors.lastname: Kowalewska
authors.affiliation: Department of Metabolic Regulation, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Radosław
authors.initials: R
authors.lastname: Mazur
authors.affiliation: Department of Metabolic Regulation, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Garstka
authors.affiliation: Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Gieczewska
authors.affiliation: Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland. Electronic address: mostowag@biol.uw.edu.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Mostowska
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism* / Q000648:ultrastructure*; D003080:Cold Temperature; D018548:Cotyledon / Q000378:metabolism / Q000648:ultrastructure; D018553:Cucumis sativus / Q000378:metabolism* / Q000648:ultrastructure; D003624:Darkness; D038983:Galactolipids / Q000378:metabolism*; D001678:Organelle Biogenesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D036226:Seedlings / Q000254:growth & development / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D038983:Galactolipids; D045332:Photosystem II Protein Complex; C007388:digalactosyldiacylglycerol; C009909:monogalactosyldiacylglycerol; D002734:Chlorophyll; D002338:Carotenoids
keywords: Chilling stress; Chloroplast biogenesis; Cotyledons; Galactolipids; Photosynthesis; Thylakoids