Improved drought tolerance without undesired side effects in transgenic plants producing trehalose |
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Authors: | Sazzad Karim Henrik Aronsson Henrik Ericson Minna Pirhonen Barbara Leyman Björn Welin Einar Mäntylä E. Tapio Palva Patrick Van Dijck Kjell-Ove Holmström |
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Affiliation: | 1.School of Life Sciences,University of Sk?vde,Sk?vde,Sweden;2.Department of Plant and Environmental Sciences,University of G?teborg,G?teborg,Sweden;3.Department of Applied Biology,University of Helsinki,Helsinki,Finland;4.Department of Molecular Microbiology,VIB, K.U. Leuven,Leuven,Belgium;5.Laboratory of Molecular Cell Biology,K.U. Leuven,Leuven,Belgium;6.Lambaré 948, Piso 3, dpto A,Buenos Aires,Argentina;7.ORF Genetics,Reykjavik,Iceland;8.Department of Biosciences, Division of Genetics,University of Helsinki,Helsinki,Finland;9.Department of Plant Biology and Forest Genetics,Swedish University of Agricultural Sciences,Uppsala,Sweden |
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Abstract: | Most organisms naturally accumulating trehalose upon stress produce the sugar in a two-step process by the action of the enzymes trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP). Transgenic plants overexpressing TPS have shown enhanced drought tolerance in spite of minute accumulation of trehalose, amounts believed to be too small to provide a protective function. However, overproduction of TPS in plants has also been found combined with pleiotropic growth aberrations. This paper describes three successful strategies to circumvent such growth defects without loosing the improved stress tolerance. First, we introduced into tobacco a double construct carrying the genes TPS1 and TPS2 (encoding TPP) from Saccharomyces cerevisiae. Both genes are regulated by an Arabidopsis RuBisCO promoter from gene AtRbcS1A giving constitutive production of both enzymes. The second strategy involved stress-induced expression by fusing the coding region of ScTPS1 downstream of the drought-inducible Arabidopsis AtRAB18 promoter. In transgenic tobacco plants harbouring genetic constructs with either ScTPS1 alone, or with ScTPS1 and ScTPS2 combined, trehalose biosynthesis was turned on only when the plants experienced stress. The third strategy involved the use of AtRbcS1A promoter together with a transit peptide in front of the coding sequence of ScTPS1, which directed the enzyme to the chloroplasts. This paper confirms that the enhanced drought tolerance depends on unknown ameliorated water retention as the initial water status is the same in control and transgenic plants and demonstrates the influence of expression of heterologous trehalose biosynthesis genes on Arabidopsis root development. |
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Keywords: | Abiotic stress Arabidopsis Improved stress tolerance Tobacco Trehalose Trehalose-6-Phosphate |
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