Phosphite primed defence responses and enhanced expression of defence genes in Arabidopsis thaliana infected with Phytophthora cinnamomi

Authors

  • L. Eshraghi,

    Corresponding author
    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, WA 6150
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  • J. Anderson,

    1. CSIRO Plant Industry, Centre for Environment and Life Sciences, Private Bag 5, Wembley, WA 6913
    2. UWA Institute of Agriculture, University of Western Australia, 35 Stirling Highway Crawley, WA 6009
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  • N. Aryamanesh,

    1. Centre for Phytophthora Science and Management, School of Plant Biology, Faculty of Natural and Agricultural Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009
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  • B. Shearer,

    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, WA 6150
    2. Science Division, Department of Environment and Conservation, Kensington, WA 6983, Australia
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  • J. McComb,

    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, WA 6150
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  • G. E. StJ. Hardy,

    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, WA 6150
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  • P. A. O’Brien

    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, WA 6150
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E-mail: L.Eshraghi@murdoch.edu.au

Abstract

This paper describes the effect of phosphite (Phi), a systemic chemical, on the induction of defence responses in Phytophthora cinnamomi-infected Arabidopsis thaliana accessions Ler and Col-0. Application of Phi to non-inoculated Athaliana seedlings of accession Ler elevated transcription of defence genes in the salicylic acid (PR1 and PR5) and jasmonic acid/ethylene (THI2.1 and PDF1.2) pathways. Furthermore, a systemic increase in the expression of the PR1 gene was demonstrated in Phi-treated seedlings using the transgenic line PR1::GUS in the presence/absence of the pathogen by 72 h after inoculation. The cells of Phi-treated A. thaliana Ler leaves responded to P. cinnamomi zoospore inoculation with a rapid increase in callose deposition and hydrogen peroxide (H2O2) production. Phi treatment resulted in the production of callose papillae 6 h earlier than in non-Phi-treated inoculated seedlings and enhanced the production of H2O2 in the leaves of A. thaliana at the site of hyphal penetration and in cells away from the inoculation point. By 24 h after infection, clear differences in the amount of H2O2 production were observed between the Phi-treated and non-Phi-treated plants. These rapid host responses did not occur in non-Phi-treated inoculated seedlings. There was also a significant (< 0·001) decrease in lesion size in Phi-treated plants. These results indicate that Phi primes the plant for a rapid and intense response to infection involving heightened activation of a range of defence responses.

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