Impact of fatty acid desaturases in Arabidopsis on the green peach aphid, myzus persicae

Fatty acid desaturases (FADs) in plants are responsible for the introduction of double bonds into the acyl chain of fatty acids, and are known to influence levels of plant resistance to many stresses, including heat and cold stress and pathogen and insect challenge. Our laboratory has previously shown that artificially suppressing expression of one FAD (FAD7) provides protection against aphid infestation in tomato (Solanum lycopersicum, Solanaceae). FAD7 is an omega-3 FAD that is localized in the chloroplast and synthesizes trienoic fatty acids (primarily C18:3 and C16:3).  In this study, we assessed whether suppressing FAD7 activity in the model plant Arabidopsis thaliana (Brassicaceae) would impact infestation by the green peach aphid, Myzus persicae.  In addition, we compared aphid performance on A. thaliana lines that carry mutations in genes encoding other FADs localized to the chloroplast or the endoplasmic reticulum. Our results indicate that FADs regulate aphid resistance in more than one plant family. We also compared the fatty acid profiles of these A. thaliana lines by gas chromatography-mass spectrometry (GC-MS) with the goal of identifying fatty acid signatures correlated with resistance or susceptibility to aphids. This study advances our understanding of the molecular and biochemical basis of aphid resistance.