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  • 1.
    Karim, Sazzad
    et al.
    University of Skövde, School of Life Sciences.
    Aronsson, Henrik
    Department of Plant and Environmental Sciences, University of Göteborg, Box 461, Göteborg 405 30, Sweden.
    Ericson, Henrik
    University of Skövde, School of Life Sciences.
    Pirhonen, Minna
    Department of Applied Biology, University of Helsinki, PL 27, Helsinki 00014, Finland.
    Leyman, Barbara
    Department of Molecular Microbiology, VIB, K.U. Leuven, Leuven, Belgium / Laboratory of Molecular Cell Biology, K.U. Leuven, Kasteelpark Arenberg 31, Leuven 3001, Belgium.
    Welin, Björn
    Lambaré 948, Dpto. A, Buenos Aires, Argentina.
    Mäntylä, Einar
    ORF Genetics, RALA-House, Keldnaholt, Reykjavik 112, Iceland.
    Palva, E. Tapio
    Department of Biosciences, Division of Genetics, University of Helsinki, P.O. Box 56, Helsinki 00014, Finland.
    Van Dijck, Patrick
    Department of Molecular Microbiology, VIB, K.U. Leuven, Leuven, Belgium / Laboratory of Molecular Cell Biology, K.U. Leuven, Kasteelpark Arenberg 31, Leuven 3001, Belgium.
    Holmström, Kjell-Ove
    University of Skövde, School of Life Sciences.
    Improved drought tolerance without undesired side effects in transgenic plants producing trehalose2007In: Plant Molecular Biology, ISSN 0167-4412, E-ISSN 1573-5028, Vol. 64, no 4, p. 371-386Article in journal (Refereed)
    Abstract [en]

    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 AtRbcS]A 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.

  • 2.
    Karim, Sazzad
    et al.
    University of Skövde, School of Life Sciences.
    Holmström, Kjell-Ove
    University of Skövde, School of Life Sciences.
    Mandal, Abul
    University of Skövde, School of Life Sciences.
    Dahl, Peter
    University of Skövde, School of Life Sciences.
    Hoffmann, Stefan
    University of Skövde, School of Life Sciences.
    Brader, Günter
    University of Skövde, School of Life Sciences.
    Palva, E. Tapio
    University of Skövde, School of Life Sciences.
    Pirhonen, Minna
    Department of Applied Biology, University of Helsinki, Box 27, 00014 Helsinki, Finland.
    AtPTR3, a wound-induced peptide transporter needed for defence against virulent bacterial pathogens in Arabidopsis2007In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 225, no 6, p. 1431-1445Article in journal (Refereed)
    Abstract [en]

    Mutation in the wound-induced peptide transporter gene AtPTR3 (At5g46050) of Arabidopsis thaliana has been shown to affect germination on media containing a high salt concentration. The heterologous expression in yeast was utilized to verify that the AtPTR3 protein transports di-and tripeptides. The T-DNA insert in the Atptr3-1 mutant in the Arabidopsis ecotype C24 revealed two T-DNA copies, the whole vector sequence, and the gus marker gene inserted in the second intron of the AtPTR3 gene. An almost identical insertion site was found in the Atptr3-2 mutant of the Col-0 ecotype. The AtPTR3 expression was shown to be regulated by several signalling compounds, most clearly by salicylic acid (SA), but also methyl jasmonate (MeJA) and abscisic acid. Real-time PCR experiments suggested that the wound-induction of the AtPTR3 gene was abolished in the SA and JA signalling mutants. The Atptr3 mutant plants had increased susceptibility to virulent pathogenic bacteria Erwinia carotovora subsp. carotovora and Pseudomonas syringae pv. tomato, and produced more reactive oxygen species when grown on media containing paraquat or rose bengal. Public microarray data suggest that the AtPTR3 expression was induced by Pseudomonas elicitors and by avirulent P. syringae pathovars and type III secretion mutants. This was verified experimentally for the hrpA mutant with real-time PCR. These results suggest that AtPTR3 is one of the defence-related genes whose expression is reduced by virulent bacterium by type III dependent fashion. Our results suggest that AtPTR3 protects the plant against biotic and abiotic stresses.

  • 3.
    Karim, Sazzad
    et al.
    University of Skövde, School of Life Sciences.
    Lundh, Dan
    University of Skövde, School of Humanities and Informatics.
    Holmström, Kjell-Ove
    University of Skövde, School of Life Sciences.
    Mandal, Abul
    University of Skövde, School of Life Sciences.
    Pirhonen, Minna
    Department of Applied Biology, University of Helsinki, Box 27, 00014 Helsinki, Finland.
    Structural and functional characterization of atPTR3, a stress-induced peptide transporter of Arabidopsis2005In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 11, no 3, p. 226-236Article in journal (Refereed)
    Abstract [en]

    A T-DNA tagged mutant line of Arabidopsis thaliana, produced with a promoter trap vector carrying a promoterless gus (uidA) as a reporter gene, showed GUS induction in response to mechanical wounding. Cloning of the chromosomal DNA flanking the T-DNA revealed that the insert had caused a knockout mutation in a PTR-type peptide transporter gene named At5g46050 in GenBank, here renamed AtPTR3. The gene and the deduced protein were characterized by molecular modelling and bioinformatics. Molecular modelling of the protein with fold recognition identified 12 transmembrane spanning regions and a large loop between the sixth and seventh helices. The structure of AtPTR3 resembled the other PTR-type transporters of plants and transporters in the major facilitator superfamily. Computer analysis of the AtPTR3 promoter suggested its expression in roots, leaves and seeds, complex hormonal regulation and induction by abiotic and biotic stresses. The computer-based hypotheses were tested experimentally by exposing the mutant plants to amino acids and several stress treatments. The AtPTR3 gene was induced by the amino acids histidine, leucine and phenylalanine in cotyledons and lower leaves, whereas a strong induction was obtained in the whole plant upon exposure to salt. Furthermore, the germination frequency of the mutant line was reduced on salt-containing media, suggesting that the AtPTR3 protein is involved in stress tolerance in seeds during germination.

1 - 3 of 3
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