Influence of Fatty Acid Desaturation on Plant Defenses Against Aphids

蚜虫是一种常见的植物害虫，以植物汁液为食，降低作物产量，并经常传播植物病原病毒。培育抗蚜虫作物品种是治理蚜虫的最有效和环境可持续的方法之一。然而，我们开发这类品种的能力受到我们对基因和生化途径的有限了解的阻碍，这些基因和生化途径控制着植物对蚜虫和其他食汁性害虫的抗性或敏感性。这个项目的目标是研究植物中的脂肪酸如何调节植物对蚜虫的防御。研究人员已经确定，在两个不同的植物物种(番茄和拟南芥)中，导致特定脂肪酸去饱和酶(FAD7)功能丧失的突变也极大地抑制了蚜虫的侵染。因此，FAD7似乎是植物对蚜虫感受性的共同调节因子。FAD7功能的丧失会导致叶子的脂肪酸组成发生戏剧性的变化，也可能会改变一系列不同类型的氧脂的产生，氧脂是一类源于脂肪酸的化合物。在番茄中，FAD7的突变似乎也会增加水杨酸的积累，水杨酸是一种已知的植物激素，可以调节植物对许多病原体的防御。新出现的大量证据表明，植物中的脂肪酸调节水杨酸依赖的防御和病原菌抗性，但其潜在机制尚未被很好地理解。这个项目将使用分子和生物化学方法来研究脂肪酸、水杨酸和特定的氧脂如何有助于植物对蚜虫的防御，以及脂肪酸如何调节水杨酸信号。最终，该项目将增进我们对植物防御的理解，并为经济上可持续的虫害管理做出贡献。此外，它还将为本科生、研究生和博士后研究人员提供培训，以及为K12科学教师提供实习机会。

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.