title: Comparative metabolic profiling of Haberlea rhodopensis, Thellungiella halophyla, and Arabidopsis thaliana exposed to low temperature.
abstract: Haberlea rhodopensis is a resurrection species with extreme resistance to drought stress and desiccation but also with ability to withstand low temperatures and freezing stress. In order to identify biochemical strategies which contribute to Haberlea's remarkable stress tolerance, the metabolic reconfiguration of H. rhodopensis during low temperature (4°C) and subsequent return to optimal temperatures (21°C) was investigated and compared with that of the stress tolerant Thellungiella halophyla and the stress sensitive Arabidopsis thaliana. Metabolic analysis by GC-MS revealed intrinsic differences in the metabolite levels of the three species even at 21°C. H. rhodopensis had significantly more raffinose, melibiose, trehalose, rhamnose, myo-inositol, sorbitol, galactinol, erythronate, threonate, 2-oxoglutarate, citrate, and glycerol than the other two species. A. thaliana had the highest levels of putrescine and fumarate, while T. halophila had much higher levels of several amino acids, including alanine, asparagine, beta-alanine, histidine, isoleucine, phenylalanine, serine, threonine, and valine. In addition, the three species responded differently to the low temperature treatment and the subsequent recovery, especially with regard to the sugar metabolism. Chilling induced accumulation of maltose in H. rhodopensis and raffinose in A. thaliana but the raffinose levels in low temperature exposed Arabidopsis were still much lower than these in unstressed Haberlea. While all species accumulated sucrose during chilling, that accumulation was transient in H. rhodopensis and A. thaliana but sustained in T. halophila after the return to optimal temperature. Thus, Haberlea's metabolome appeared primed for chilling stress but the low temperature acclimation induced additional stress-protective mechanisms. A diverse array of sugars, organic acids, and polyols constitute Haberlea's main metabolic defence mechanisms against chilling, while accumulation of amino acids and amino acid derivatives contribute to the low temperature acclimation in Arabidopsis and Thellungiella. Collectively, these results show inherent differences in the metabolomes under the ambient temperature and the strategies to respond to low temperature in the three species.
authors.affiliation: Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv Plovdiv, Bulgaria ; Institute of Molecular Biology and Biotechnology Plovdiv, Bulgaria.
authors.forename: Maria
authors.initials: M
authors.lastname: Benina
authors.affiliation: Department Willmitzer, Max Planck Institute of Molecular Plant Physiology Potsdam-Golm, Germany.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Obata
authors.affiliation: Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv Plovdiv, Bulgaria ; Institute of Molecular Biology and Biotechnology Plovdiv, Bulgaria.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Mehterov
authors.affiliation: Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv Plovdiv, Bulgaria.
authors.forename: Ivan
authors.initials: I
authors.lastname: Ivanov
authors.affiliation: Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv Plovdiv, Bulgaria ; Institute of Molecular Biology and Biotechnology Plovdiv, Bulgaria.
authors.forename: Veselin
authors.initials: V
authors.lastname: Petrov
authors.affiliation: Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv Plovdiv, Bulgaria ; Institute of Molecular Biology and Biotechnology Plovdiv, Bulgaria.
authors.forename: Valentina
authors.initials: V
authors.lastname: Toneva
authors.affiliation: Department Willmitzer, Max Planck Institute of Molecular Plant Physiology Potsdam-Golm, Germany.
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.affiliation: Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv Plovdiv, Bulgaria ; Institute of Molecular Biology and Biotechnology Plovdiv, Bulgaria ; Department of Molecular Biology, Institute of Biochemistry and Biology, University of Potsdam Potsdam, Germany.
authors.forename: Tsanko S
authors.initials: TS
authors.lastname: Gechev
keywords: Arabidopsis thaliana; Haberlea rhodopensis; Thellungiella halophila; low temperature stress; metabolite profiling