title: Transgenic tobacco plants accumulating osmolytes show reduced oxidative damage under freezing stress.
abstract: We studied the reaction to the oxidative component of freezing in several tobacco lines, transformed with genes coding for enzymes involved in the synthesis of osmoprotectants (proline, fructan or glycine betaine) along with their wild type. The levels of some oxidative stress markers (leakage of electrolytes, hydrogen peroxide and malondialdehyde) as well as the activity of antioxidative enzymes catalase (EC 1.11.1.6.) and guaiacol peroxidase (EC 1.11.1.7.) have been followed at acclimation, 12 and 24 h freezing and at recovery. Freezing for 24 h resulted in severe damages for the wild type. A corresponding increase of electrolyte leakage, hydrogen peroxide and malondialdehyde contents, a rise of peroxidase activity and inhibition of catalase activity occurred in the non-transformants. Similar, but significantly lower trend of the same parameters has been found for the transgenic lines. Moreover, the oxidative markers returned to their normal levels when the transformants were able to recover from freezing. It could be speculated that transfer of genes, coding for accumulation of osmoprotectants, is related to reduced intensity of freezing-induced oxidative processes. Our lines and model system could serve as a good prerequisite for additional studies to gain further insights into the complex role of osmoprotectants in freezing tolerance.
authors.affiliation: Abiotic Stress Tolerance and Echophysiology, AgroBioInstitute, Institute of Cryobiology and Food Technology, Sofia, Bulgaria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Parvanova
authors.forename: Sergei
authors.initials: S
authors.lastname: Ivanov
authors.forename: Tatyana
authors.initials: T
authors.lastname: Konstantinova
authors.forename: Emanuil
authors.initials: E
authors.lastname: Karanov
authors.forename: Atanas
authors.initials: A
authors.lastname: Atanassov
authors.forename: Tsvetan
authors.initials: T
authors.lastname: Tsvetkov
authors.forename: Vera
authors.initials: V
authors.lastname: Alexieva
authors.forename: Dimitar
authors.initials: D
authors.lastname: Djilianov
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D001622:Betaine / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism*; D005615:Freezing; D005630:Fructans / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000502:physiology*; D011392:Proline / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014882:Water-Electrolyte Balance
chemical_list: D004573:Electrolytes; D005630:Fructans; D001622:Betaine; D008315:Malondialdehyde; D011392:Proline; D006861:Hydrogen Peroxide; C121048:guaiacol peroxidase; D002374:Catalase; D009195:Peroxidase