Articles
NEW APPROACHES TO THE DEVELOPMENT OF TRANSGENIC PLANTS RESISTANT TO FIRE BLIGHT
Article number
489_52
Pages
301 – 306
Language
Abstract
Recent discoveries in our laboratories and orchards have resulted in new approaches for the development of fire blight-resistant transgenic plants.
Harpin, a protein produced by Erwinia amylovora, elicits a hypersensitive response following infiltration into the leaf intercellular spaces of many plants.
Exogenous application of harpin results in useful levels of systemic acquired resistance (SAR) in most plants tested, including apple.
We are now testing transgenic Arabidopsis thaliana and apple expressing hrpN, for constitutive expression of SAR, or elicitation of HR specifically in response to pathogen stimulation.
Several multi-component plant transformation constructs were developed.
In one, the nos promoter, a weak constitutive promoter from Agrobacterium tumefaciens, was used to drive the hrpN gene to elicit SAR. In another, the Gst1 promoter, a pathogen-inducible promoter from potato, was used to drive the hrpN gene for elicitation of HR in response to pathogen stimulation.
Both constructs were made with or without a signal sequence for export of harpin to the plant intercellular spaces.
Transgenic Arabidopsis plants containing the Gstl promoter-hrpN constructs showed increased resistance to downy mildew caused by Peronospora parasitica. We are evaluating the same constructs in transgenic apple for the ability to confer resistance to fire blight.
Harpin, a protein produced by Erwinia amylovora, elicits a hypersensitive response following infiltration into the leaf intercellular spaces of many plants.
Exogenous application of harpin results in useful levels of systemic acquired resistance (SAR) in most plants tested, including apple.
We are now testing transgenic Arabidopsis thaliana and apple expressing hrpN, for constitutive expression of SAR, or elicitation of HR specifically in response to pathogen stimulation.
Several multi-component plant transformation constructs were developed.
In one, the nos promoter, a weak constitutive promoter from Agrobacterium tumefaciens, was used to drive the hrpN gene to elicit SAR. In another, the Gst1 promoter, a pathogen-inducible promoter from potato, was used to drive the hrpN gene for elicitation of HR in response to pathogen stimulation.
Both constructs were made with or without a signal sequence for export of harpin to the plant intercellular spaces.
Transgenic Arabidopsis plants containing the Gstl promoter-hrpN constructs showed increased resistance to downy mildew caused by Peronospora parasitica. We are evaluating the same constructs in transgenic apple for the ability to confer resistance to fire blight.
The DspE protein from E. amylovora is homologous to AvrE, an avirulence protein, from Pseudomonas syringae pv. tomato. The gene, dspE, is required by E. amylovora for pathogenicity, but it acts as an avirulence gene in P. syringae pv. glycinea. Several A. thaliana ecotypes have been identified that were resistant to Pseudomonas syringae pv. tomato, strain DC3000, only when it contained a clone of dspE. We are currently mapping the Arabidopsis gene to clone it by a map-based approach.
The cloned gene will be used as a resistance gene to create transgenic plants and evaluate their resistance to fire blight.
Publication
Authors
D.W. Bauer, E.R. Garr, S.V. Beer, J.L. Norelli, H.S. Aldwinckle
Keywords
Erwinia amylovora, Arabidopsis thaliana, apple, hypersensitive response, systemic acquired resistance
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