title: Silencing S-Adenosyl-L-Methionine Decarboxylase (SAMDC) in Nicotiana tabacum Points at a Polyamine-Dependent Trade-Off between Growth and Tolerance Responses.
abstract: Polyamines (PAs) are nitrogenous molecules that are indispensable for cell viability and with an agreed-on role in the modulation of stress responses. Tobacco plants with downregulated SAMDC (AS-SAMDC) exhibit reduced PAs synthesis but normal levels of PA catabolism. We used AS-SAMDC to increase our understanding on the role of PAs in stress responses. Surprisingly, at control conditions AS-SAMDC plants showed increased biomass and altered developmental characteristics, such as increased height and leaf number. On the contrary, during salt stress AS-SAMDC plants showed reduced vigor when compared to the WT. During salt stress, the AS-SAMDC plants although showing compensatory readjustments of the antioxidant machinery and of photosynthetic apparatus, they failed to sustain their vigor. AS-SAMDC sensitivity was accompanied by inability to effectively control H2O2 levels and concentrations of monovalent and divalent cations. In accordance with these findings, we suggest that PAs may regulate the trade-off between growth and tolerance responses.
authors.affiliation: Department of Crop Production, School of Agriculture, Aristotle University of Thessaloniki Thessaloniki, Greece.
authors.forename: Ifigeneia
authors.initials: I
authors.lastname: Mellidou
authors.affiliation: Department of Plant Biology and Linnean Center of Plant Sciences, Uppsala BioCentrum, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Panagiotis N
authors.initials: PN
authors.lastname: Moschou
authors.affiliation: Department of Biology, University of Crete Heraklion, Greece.
authors.forename: Nikolaos E
authors.initials: NE
authors.lastname: Ioannidis
authors.affiliation: Department of Crop Production, School of Agriculture, Aristotle University of Thessaloniki Thessaloniki, Greece.
authors.forename: Chryssa
authors.initials: C
authors.lastname: Pankou
authors.affiliation: Biological Research Centre, Hungarian Academy of Sciences Szeged, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Gėmes
authors.affiliation: Department of Biology, National and Kapodistrian University of Athens Athens, Greece.
authors.forename: Chryssanthi
authors.initials: C
authors.lastname: Valassakis
authors.affiliation: Department of Biology, University of Crete Heraklion, Greece.
authors.forename: Efthimios A
authors.initials: EA
authors.lastname: Andronis
authors.affiliation: Department of Biology, National and Kapodistrian University of Athens Athens, Greece.
authors.forename: Despoina
authors.initials: D
authors.lastname: Beris
authors.affiliation: Department of Biology, National and Kapodistrian University of Athens Athens, Greece.
authors.forename: Kosmas
authors.initials: K
authors.lastname: Haralampidis
authors.affiliation: Department of Biology, National and Kapodistrian University of Athens Athens, Greece.
authors.forename: Andreas
authors.initials: A
authors.lastname: Roussis
authors.affiliation: Department of Crop Production, School of Agriculture, Aristotle University of Thessaloniki Thessaloniki, Greece.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Karamanoli
authors.affiliation: Department of Crop Production, School of Agriculture, Aristotle University of Thessaloniki Thessaloniki, Greece.
authors.forename: Theodora
authors.initials: T
authors.lastname: Matsi
authors.affiliation: Department of Biology, University of Crete Heraklion, Greece.
authors.forename: Kiriakos
authors.initials: K
authors.lastname: Kotzabasis
authors.affiliation: Department of Crop Production, School of Agriculture, Aristotle University of Thessaloniki Thessaloniki, Greece.
authors.forename: Helen-Isis
authors.initials: HI
authors.lastname: Constantinidou
authors.affiliation: Department of Biology, University of Crete Heraklion, Greece.
authors.forename: Kalliopi A
authors.initials: KA
authors.lastname: Roubelakis-Angelakis
keywords: ROS; SAMDC transgenics; polyamine metabolism; salt tolerance; silenced SAMDC; transgenic assessment