Trees manifest two different types of defense against insects and pathogens: constitutive (pre-attack) and induced (post-attack). Constitutive defenses include the physical barrier represented by the outer bark as well as defensive proteins and specialized metabolites, such as phenolics, toxic to the insect. Induced defenses include the formation of necrophylactic periderm and the induced accumulation of phenolics, lignin and defensive proteins. The invasive emerald ash borer (EAB) beetle is threatening to decimate North America’s ash population. In previous work, we identified putative biochemical and molecular markers of constitutive EAB resistance in Manchurian ash, an Asian species that is resistant by virtue of coevolution with EAB. Recently, we characterized a pinoresinol-type phenolic biomarker for induced resistance in ash subjected to both inoculation with EAB eggs and water stress. To further investigate induced defense responses, we performed high throughput semi-quantitative comparative proteomics of tissue from the same experiment. Proteins from forty trees (2 species × 2 water treatments × 2 insect egg treatments × 5 biological replicates) were precipitated, cleaned and subjected to two dimensional difference gel electrophoresis (2D-DIGE). Protein spots were chosen based on DeCyder software and multivariate statistics using a 5-fold change cut-off. Selected protein spots were digested using trypsin and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The proteins were searched against the green plant database, Viridiplantae using the MASCOT search engine. Using this approach we were able to identify twenty eight proteins from phloem tissue of two ash species that were induced by EAB larval attack.

Induced resistance in ash (<i>Fraxinus spp</i>.) against emerald ash borer:  A proteomic investigation

249th National Meeting (2015)

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Induced resistance in ash (Fraxinus spp.) against emerald ash borer: A proteomic investigation