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Manipulation of salicylate content in Arabidopsis thaliana by the expression of an engineered bacterial salicylate synthase.

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  • 2001-02-13
Published in:
  • The Plant journal : for cell and molecular biology. - 2001
Amino Acid Sequence
Arabidopsis
Base Sequence
Caulimovirus
Codon
Intramolecular Transferases
Lyases
Molecular Sequence Data
Phenols
Plant Leaves
Plants, Genetically Modified
Pseudomonas aeruginosa
Recombinant Fusion Proteins
Restriction Mapping
Salicylates
Thiazoles
English Salicylic acid (SA) plays a central role as a signalling molecule involved in plant defense against microbial attack. Genetic manipulation of SA biosynthesis may therefore help to generate plants that are more disease-resistant. By fusing the two bacterial genes pchA and pchB from Pseudomonas aeruginosa, which encode isochorismate synthase and isochorismate pyruvate-lyase, respectively, we have engineered a novel hybrid enzyme with salicylate synthase (SAS) activity. The pchB-A fusion was expressed in Arabidopsis thaliana under the control of the constitutive cauliflower mosaic virus (CaMV) 35S promoter, with targeting of the gene product either to the cytosol (c-SAS plants) or to the chloroplast (p-SAS plants). In p-SAS plants, the amount of free and conjugated SA was increased more than 20-fold above wild type (WT) level, indicating that SAS is functional in Arabidopsis. P-SAS plants showed a strongly dwarfed phenotype and produced very few seeds. Dwarfism could be caused by the high SA levels per se or, perhaps more likely, by a depletion of the chorismate or isochorismate pools of the chloroplast. Targeting of SAS to the cytosol caused a slight increase in free SA and a significant threefold increase in conjugated SA, probably reflecting limited chorismate availability in this compartment. Although this modest increase in total SA content did not strongly induce the resistance marker PR-1, it resulted nevertheless in enhanced disease resistance towards a virulent isolate of Peronospora parasitica. Increased resistance of c-SAS lines was paralleled with reduced seed production. Taken together, these results illustrate that SAS is a potent tool for the manipulation of SA levels in plants.
Language
  • English
Open access status
green
Identifiers
Persistent URL
https://sonar.ch/global/documents/189267
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