title: Soybean Aphid Infestation Induces Changes in Fatty Acid Metabolism in Soybean.
abstract: The soybean aphid (Aphis glycines Matsumura) is one of the most important insect pests of soybeans in the North-central region of the US. It has been hypothesized that aphids avoid effective defenses by inhibition of jasmonate-regulated plant responses. Given the role fatty acids play in jasmonate-induced plant defenses, we analyzed the fatty acid profile of soybean leaves and seeds from aphid-infested plants. Aphid infestation reduced levels of polyunsaturated fatty acids in leaves with a concomitant increase in palmitic acid. In seeds, a reduction in polyunsaturated fatty acids was associated with an increase in stearic acid and oleic acid. Soybean plants challenged with the brown stem rot fungus or with soybean cyst nematodes did not present changes in fatty acid levels in leaves or seeds, indicating that the changes induced by aphids are not a general response to pests. One of the polyunsaturated fatty acids, linolenic acid, is the precursor of jasmonate; thus, these changes in fatty acid metabolism may be examples of "metabolic hijacking" by the aphid to avoid the induction of effective defenses. Based on the changes in fatty acid levels observed in seeds and leaves, we hypothesize that aphids potentially induce interference in the fatty acid desaturation pathway, likely reducing FAD2 and FAD6 activity that leads to a reduction in polyunsaturated fatty acids. Our data support the idea that aphids block jasmonate-dependent defenses by reduction of the hormone precursor.
authors.affiliation: Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Charles
authors.initials: C
authors.lastname: Kanobe
authors.affiliation: Department of Entomology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Michael T
authors.initials: MT
authors.lastname: McCarville
authors.affiliation: Department of Entomology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: O'Neal
authors.affiliation: Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Tylka
authors.affiliation: Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Gustavo C
authors.initials: GC
authors.lastname: MacIntosh
mesh_terms: D000818:Animals; D001042:Aphids / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism*; D006790:Host-Parasite Interactions; D050356:Lipid Metabolism; D009348:Nematoda / Q000502:physiology; D010935:Plant Diseases / Q000469:parasitology; D018515:Plant Leaves / Q000378:metabolism / Q000469:parasitology; D013025:Glycine max / Q000378:metabolism / Q000469:parasitology*
chemical_list: D005227:Fatty Acids