title: Effects of exogenously applied hydrogen peroxide on antioxidant and osmoprotectant profiles and the C3-CAM shift in the halophyte Mesembryanthemum crystallinum L.
abstract: Exogenously applied H2O2 (50, 100 and 200mM) to Mesembryanthemum crystallinum root medium induced a transition from C3 to Crassulacean Acid Metabolism (CAM), as evaluated by diurnal malate (Δmal) fluctuations. A very high concentration of H2O2 (400mM) reduced Δmal below the value measured in control plants. An increase of malate content during the night in 400mM H2O2-treated plants might suggest that malate decarboxylation is crucial for CAM functioning. We conclude that malate plays a dual role: i) a protective and signaling function before CAM expression, and ii) a storage form of CO2 in plants performing CAM. A slight stimulation of photosystem II (PSII) photochemistry and net photosynthesis observed during the C3-CAM shift indicated that neither photoinhibition nor reduction of the photosynthetic rate were prerequisites for CAM. Moreover, CAM induction corresponded to a decrease of catalase activity. In CAM-performing plants, α-tocopherol, polyamines (putrescine and spermidine) and proline showed daily alterations and the content of α-tocopherol and polyamines was lower at the end of the day. In contrast, the proline concentration correlated with the applied H2O2 concentration and was higher at the end of the day in treated plants. The dynamic changes of antioxidant and osmolyte levels suggest their active role in preventing oxidative damage, stress acclimation mechanisms and involvement in metabolic regulation and/or signal transduction cascades.
authors.affiliation: The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Kraków, Poland. Electronic address: ewa.surowka@gmail.com.
authors.forename: Ewa
authors.initials: E
authors.lastname: Surówka
authors.affiliation: The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Kraków, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Dziurka
authors.affiliation: Institute of Biology, Jan Kochanowski University, ul. Świętokrzyska 15, 25-406 Kielce, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Kocurek
authors.affiliation: Pedagogical University of Kraków, Podchorążych 2, 30-084 Kraków, Poland.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Goraj
authors.affiliation: University of Agriculture, Al. Mickiewicza 21, 31-120 Kraków, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Rapacz
authors.affiliation: The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Kraków, Poland; Malopolska Center of Biotechnology, Jagiellonian University, ul. Gronostajowa 7A, 30-387 Kraków, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Miszalski
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002264:Carboxylic Acids / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D005740:Gases / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D035723:Mesembryanthemum / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D009995:Osmosis / Q000187:drug effects*; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000502:physiology*; D013312:Stress, Physiological / Q000187:drug effects; D024502:alpha-Tocopherol / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002264:Carboxylic Acids; D005740:Gases; D045332:Photosystem II Protein Complex; D011073:Polyamines; D002244:Carbon; D011392:Proline; D006861:Hydrogen Peroxide; D002374:Catalase; D024502:alpha-Tocopherol
keywords: Catalase; Malate; Photosynthesis; Polyamines; Proline; α-Tocopherol