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，并经常传播植物致病性病毒。培育抗蚜作物品种是防治蚜虫最有效和环境可持续的方法之一。然而，由于我们对控制植物对蚜虫和其他取食汁液的害虫的抗性或易感程度的基因和生化途径的知识有限，我们开发这类品种的能力受到了阻碍。该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，在两种不同的植物物种（番茄和拟南芥）中，导致一种特定脂肪酸去饱和酶（FAD7）功能丧失的突变也能显著抑制蚜虫的侵袭。因此，FAD7似乎是植物对蚜虫易感性的共同调节因子。FAD7功能的丧失会导致叶片脂肪酸组成的剧烈变化，并且可能也会改变多种氧化脂素的产生，氧化脂素是一种来源于脂肪酸的化合物。在番茄中，FAD7的突变似乎也增加了水杨酸的积累，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。越来越多的证据表明，植物中的脂肪酸调节水杨酸依赖性防御和病原体抗性，但其潜在机制尚未得到很好的理解。该项目将利用分子和生化方法研究脂肪酸、水杨酸和特定的氧脂素如何促进植物防御蚜虫，以及脂肪酸如何调节水杨酸信号传导。最终，该项目将提高我们对植物防御的认识，并为经济可持续的害虫管理做出贡献。此外，它还将为本科生和研究生以及博士后研究人员提供培训，并为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.