Testing of a heterologous, wound- and insect-inducible promoter for functional genomics studies in conifer defense
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Large-scale sequencing of conifer cDNAs and targeted molecular cloning have identified many putative conifer defense genes. Expression of many of these genes is induced in response to biotic stress and some may be expressed only in a few specialized tissues or cells. Proven functional genomics approaches to test these genes involve expression of proteins in Escherichia coli or yeast for biochemical characterization or constitutive over-expression in transformed plants. Plant transformation to test functions of insect-, wound- or pathogen-induced conifer defense genes would benefit from the use of an inducible expression system. We describe here the development of a heterologous, wound- and insect-inducible gene expression system for conifers using the potato proteinase inhibitor II (pinII)-promoter. Using pinII::GUS and pinII::(E)-α-bisabolene synthase expression constructs we demonstrate localized induced gene expression in white spruce seedlings (Picea glauca). Testing of these constructs in Arabidopsis thaliana and tobacco illustrates the additional potential of the pinII-promoter to be used in tests of gene function that involve cell-specific and systemic induction.
KeywordsLocal and systemic defense Metabolic engineering Oleoresin Plant–insect interactions Secondary metabolism Terpenoid synthase
The research reported in this paper was supported with grants from the Natural Sciences and Engineering Research Council of Canada (NSERC; Jörg Bohlmann and Aine Plant) and by funds from Genome British Columbia and Genome Canada in support of the TREENOMIX Conifer Forest Health Project (grant to Jörg Bohlmann). Conifer transformation in the laboratory of Armand Séguin was supported by the Arborea Project funded by Genome Québec and Genome Canada. We thank Dr. Rodney Croteau, Washington State University, Pullman, USA for providing the grand fir (E)-α-bisabolene synthase cDNA clone. We thank Gholamreza Babajani, Harpreet Sandhu and Françoise Pelletier for technical assistance. Kimberley-Ann Godard was supported by an NSERC graduate student scholarship. Jörg Bohlmann is an NSERC E.W.R. Steacie Memorial fellow.
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