The Role of a Membrane Channel in Conferring Fluoride Resistance in Plants

氟化物是地壳中含量第13丰富的元素。 自然和工业来源有助于土壤，水和空气中的氟化物水平。 虽然对氟化物没有生物学需求，但低浓度的氟化物可以提高动物的牙齿质量。 然而，在某些情况下，氟化物是有毒的。毒性取决于多种因素，包括浓度，暴露时间和生物体本身。 氟敏感植物如唐菖蒲在20 ppm（1 mM）的浓度下受到伤害，而高于1200 ppm（63 mM）的浓度对耐氟茶树没有可观察到的影响。 保护单细胞生物免受氟化物毒性是通过一种称为FEX（氟化物输出器）的膜通道从细胞中去除氟离子来实现的。 最近在包括植物在内的多细胞生物中发现了编码这种氟化物通道的基因。 植物特别容易受到氟化物的影响，因为它们暴露于土壤，水和空气中的氟化物。 此外，用于促进植物生长的磷肥是污染氟化物的来源，因为它们是由含有氟化物的磷酸盐岩生产的。 研究植物中假定的氟化物通道将拓宽我们对它们如何避免氟化物毒性的理解。 这些知识将有助于保护作物免受氟化物的侵害，并可能降低特定植物组织中的氟化物浓度。 与耶鲁大学科学之路项目合作，初中和高中学生将通过全天的节日，深入的研讨会和广泛的夏季实验室体验来探索植物生物学和科学方法。 本研究探讨了FEX如何有助于植物耐氟性。已经在酵母FEX敲除中测试了来自几种植物的推定的氟化物通道，并且发现其提供与天然酵母FEX相似水平的氟化物耐受性。 此外，拟南芥中FEX的缺失在正常植物生长条件下是致命的。 将使用各种活力和生长测定来评估植物中FEX水平改变的影响。 FEX如何影响氟化物通过植物的传播将使用18F和正电子发射断层扫描（PET）进行监测。 此外，将使用细胞特异性启动子操纵FEX的表达，以确定植物是否采用协调的高阶策略进行氟化物调节，或将受益于这种策略。 这项工作将确定植物如何积累和消散氟化物以及FEX在这一过程中的作用。将获得关于如何使用FEX改善氟化物解毒的信息。 它代表了FEX和多细胞生物体中氟化物流出的首次研究。 这些实验将提供FEX通过差异调节将氟化物引导到特定组织或从特定组织引导氟化物的能力的见解，为植物中氟化物毒性的表征创建基线，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查进行评估，被认为值得支持的搜索.

Fluoride is the 13th-most abundant element in the Earth’s crust. Natural and industrial sources contribute to fluoride levels in the soil, water, and air. While there is no biological requirement for fluoride, low concentrations of fluoride enhance teeth quality in animals. However, under certain conditions, fluoride is toxic. Toxicity depends on multiple factors including concentration, exposure time, and the organism itself. Fluoride-sensitive plants like Gladiolus are injured at a concentration of 20 ppm (1 mM), while concentrations above 1200 ppm (63 mM) have no observable effects on the fluoride-tolerant tea plant. Protection against fluoride toxicity in single-celled organisms is achieved by removing fluoride ions from the cell through a membrane channel called FEX (Fluoride Exporter). A gene encoding this fluoride channel has been recently identified in multicellular organisms, including plants. Plants are particularly vulnerable to fluoride because they are exposed to fluoride from the soil, water, and air. In addition, phosphate fertilizers used to enhance plant growth are sources of contaminating fluoride because they are produced from rock phosphate, which contains fluoride. Studying the putative fluoride channel in plants will broaden our understanding of how they avoid fluoride toxicity. This knowledge will help to protect crop plants from fluoride and possibly reduce the concentration of fluoride in specific plant tissues. In cooperation with the Yale Pathways to Science program, middle- and high- school students will explore plant biology and the scientific method through an all-day festival, in-depth workshops, and extensive summer laboratory experiences. This research investigates how FEX contributes to fluoride tolerance in plants. Putative fluoride channels from several plants have been tested in a yeast FEX knockout and found to provide fluoride tolerance to a level similar to native yeast FEX. In addition, deletion of FEX in Arabidopsis is lethal in normal plant growth conditions. A variety of viability and growth assays will be used to assess the effect of altered levels of FEX in plants. How FEX affects fluoride travels through plants will be monitored using 18F and Positron Emission Tomography (PET). Additionally, the expression of FEX will be manipulated using cell-specific promoters to ascertain whether plants employ, or would benefit from, a coordinated higher-order strategy for fluoride regulation. This work will establish how the plant accumulates and dissipates fluoride and the role of FEX in that process. Information will be obtained on how to improve fluoride detoxification using FEX. It represents the first study of FEX and fluoride efflux in a multicellular organism. These experiments will provide insights into the ability of FEX to direct fluoride to or from specific tissues through differential regulation, create a baseline for characterization of fluoride toxicity in plants, and open up new areas of study for fluoride detoxification and bioremediation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.