Influence of Fatty Acid Desaturation on Plant Defenses Against Aphids

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Aphids are a common pest of plants that feed on plant sap, reducing crop yields and frequently transmitting plant-pathogenic viruses. Cultivation of crop varieties that are resistant to aphids is one of the most effective and environmentally sustainable approaches to aphid pest management. However, our ability to develop such cultivars is hampered by our limited knowledge of the genes and biochemical pathways that control how resistant or susceptible plants are to aphids and other sap-feeding pests. The goal of this project is to investigate how fatty acids in plants may regulate plant defenses against aphids. The investigators have determined that in two different plant species (tomato and Arabidopsis), mutations that cause loss of function of a particular fatty acid desaturase (FAD7) also dramatically inhibit aphid infestation. Thus, FAD7 appears to be a common regulator of plant susceptibility to aphids. Loss of function of FAD7 causes dramatic changes in the fatty acid composition of the foliage, and likely also alters production of a diverse array of oxylipins, a family of compounds derived from fatty acids. In tomato, mutation of FAD7 also appears to enhance accumulation of salicylic acid, a plant hormone known to mediate plant defenses against many pathogens. An emerging body of evidence indicates that fatty acids in plants regulate salicylic acid-dependent defenses and pathogen resistance, but the underlying mechanisms are not yet well-understood. This project will use molecular and biochemical approaches to investigate how fatty acids, salicylic acid, and specific oxylipins contribute to plant defenses against aphids, and how fatty acids regulate salicylic acid signaling. Ultimately, this project should enhance our understanding of plant defense and contribute to economically sustainable pest management. In addition, it will provide training for undergraduate and graduate students and postdoctoral researchers, as well as internship opportunities for K12 science teachers.