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Open Access Publications from the University of California

Petunia hybrida PDR2 is involved in herbivore defense by controlling steroidal contents in trichomes.

  • Author(s): Sasse, Joëlle;
  • Schlegel, Markus;
  • Borghi, Lorenzo;
  • Ullrich, Friederike;
  • Lee, Miyoung;
  • Liu, Guo-Wei;
  • Giner, José-Luis;
  • Kayser, Oliver;
  • Bigler, Laurent;
  • Martinoia, Enrico;
  • Kretzschmar, Tobias
  • et al.

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As a first line of defense against insect herbivores many plants store high concentrations of toxic and deterrent secondary metabolites in glandular trichomes. Plant Pleiotropic Drug Resistance (PDR)-type ABC transporters are known secondary metabolite transporters, and several have been implicated in pathogen or herbivore defense. Here, we report on Petunia hybrida PhPDR2 as a major contributor to trichome-related chemical defense. PhPDR2 was found to localize to the plasma membrane and be predominantly expressed in multicellular glandular trichomes of leaves and stems. Down-regulation of PhPDR2 via RNA interference (pdr2) resulted in a markedly higher susceptibility of the transgenic plants to the generalist foliage feeder Spodoptera littoralis. Untargeted screening of pdr2 trichome metabolite contents showed a significant decrease in petuniasterone and petuniolide content, compounds, which had previously been shown to act as potent toxins against various insects. Our findings suggest that PhPDR2 plays a leading role in controlling petuniasterone levels in leaves and trichomes of petunia, thus contributing to herbivory resistance.

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