Plants on early alert: glandular trichomes as sensors for insect herbivores.
The ability of caterpillar or moth 'footsteps' to elicit defenses in the tomato (Solanum lycopersicum) plant was examined. Although touch responses frequently have been observed in plants, the role of herbivore 'touch' in eliciting antiherbivore defenses has not been adequately examined. A combination of methods, including in situ hybridization, reverse transcriptase-polymerase chain reaction, quantitative real-time polymerase chain reaction and gas chromatography-mass spectrometry, was used to determine the role of trichomes in mediating these touch responses. Mutants compromised in jasmonic acid and glandular trichomes were used to test whether both of these were required for these touch responses. We demonstrated that the rupture of foliar glandular trichomes by caterpillar or moth contact induced the expression of defense transcripts (e.g. proteinase inhibitor 2, or PIN2) regulated by jasmonic acid. Neither chewing nor the release of salivary components was required to initiate this induced response. Jasmonic acid and the genes encoding proteins involved in its biosynthesis were identified in the trichomes. Using mutants, we showed that both jasmonic acid and trichomes were required for the contact-induced expression of PIN2. In addition, hydrogen peroxide, formed on the leaf surface, was required for PIN2 expression. Because these defenses would be activated before egg hatch, this early detection system for herbivores may be of considerable ecological significance.
Peiffer
Michelle
M
Department of Entomology and Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
Tooker
John F
JF
Department of Entomology and Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
Luthe
Dawn S
DS
Department of Crop and Soil Science and Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
Felton
Gary W
GW
Department of Entomology and Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
D000818:Animals; D001483:Base Sequence; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D009036:Moths / Q000502:physiology*; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism / Q000494:pharmacology; D019441:Plant Epidermis / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D014110:Touch / Q000502:physiology
D003517:Cyclopentanes; D017931:DNA Primers; D018744:DNA, Plant; D054883:Oxylipins; D010940:Plant Proteins; C034104:proteinase inhibitor II protein, plant; C011006:jasmonic acid; D006861:Hydrogen Peroxide
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