Transcription factor MYC2 is involved in priming for enhanced defense during rhizobacteria-induced systemic resistance in Arabidopsis thaliana

Authors

  • Maria J. Pozo,

    1. Graduate School Experimental Plant Sciences, Plant–Microbe Interactions, Institute of Environmental Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, the Netherlands;
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    • *

      These authors contributed equally to this work.

  • Sjoerd Van Der Ent,

    1. Graduate School Experimental Plant Sciences, Plant–Microbe Interactions, Institute of Environmental Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, the Netherlands;
    2. Center for Biosystems Genomics, PO Box 98, 6700 AB Wageningen, the Netherlands
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    • *

      These authors contributed equally to this work.

  • L. C. Van Loon,

    1. Graduate School Experimental Plant Sciences, Plant–Microbe Interactions, Institute of Environmental Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, the Netherlands;
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  • Corné M. J. Pieterse

    1. Graduate School Experimental Plant Sciences, Plant–Microbe Interactions, Institute of Environmental Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, the Netherlands;
    2. Center for Biosystems Genomics, PO Box 98, 6700 AB Wageningen, the Netherlands
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Author for correspondence:
Corné M. J. Pieterse
Tel: +31 30 253 6887
Fax: +31 30 253 2837
Email: C.M.J.Pieterse@uu.nl

Summary

  • • Upon appropriate stimulation, plants can develop an enhanced capacity to express infection-induced cellular defense responses, a phenomenon known as the primed state. Colonization of the roots of Arabidopsis thaliana by the beneficial rhizobacterial strain Pseudomonas fluorescens WCS417r primes the leaf tissue for enhanced pathogen- and insect-induced expression of jasmonate (JA)-responsive genes, resulting in an induced systemic resistance (ISR) that is effective against different types of pathogens and insect herbivores.
  • • Here the molecular mechanism of this rhizobacteria-induced priming response was investigated using a whole-genome transcript profiling approach.
  • • Out of the 1879 putative methyl jasmonate (MeJA)-responsive genes, 442 genes displayed a primed expression pattern in ISR-expressing plants. Promoter analysis of ISR-primed, MeJA-responsive genes and ISR-primed, Pseudomonas syringae pv. tomato DC3000 (Pst DC3000)-responsive genes revealed over-representation of the G-box-like motif 5′-CACATG-3′. This motif is a binding site for the transcription factor MYC2, which plays a central role in JA- and abscisic acid-regulated signaling. MYC2 expression was consistently up-regulated in ISR-expressing plants. Moreover, mutants impaired in the JASMONATE-INSENSITIVE1/MYC2 gene (jin1-1 and jin1-2) were unable to mount WCS417r-ISR against Pst DC3000 and the downy mildew pathogen Hyaloperonospora parasitica.
  • • Together, these results pinpoint MYC2 as a potential regulator in priming for enhanced JA-responsive gene expression during rhizobacteria-mediated ISR.

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