Mechanisms underlying arsenic tolerance and hyperaccumulation in the fern Pteris vittata

砷是一种天然存在的有毒金属，已知如果摄入会导致癌症。土壤和水的砷污染是包括美国在内的世界许多地区的一个环境问题。这项研究的重点是蕨类植物凤尾草，这是值得注意的，因为它和它的近亲是唯一已知的能够耐受和积累非常高水平砷的多细胞生物。这项研究的目标是了解这种植物如何能够在不屈服于其致命影响的情况下吸收和储存这种毒素。从这种植物中分离出的两个基因被推测参与了这一过程。一种是砷酸还原酶，它能将根部从土壤中吸收的砷还原为亚砷酸盐。另一种是亚砷酸盐喷射器，它被认为是将亚砷酸盐移动到细胞的液泡中，在那里它被安全地隔离。这项研究的一个目标是在另一种对砷敏感的植物(拟南芥)中表达这些基因，看看它们是否能够赋予其他植物耐砷能力。第二个目标是将这些基因产生的蛋白质定位在组织、细胞和亚细胞水平上。最终的目标是开发基本的植物基因组工具，最终将使我们能够识别与这种植物的耐砷和超积累有关的其他基因。这项研究具有更广泛的影响，因为它将确定砷的耐受和积累机制，这可能在修复受砷污染的土壤中具有实用价值。这项研究还将为本科生和研究生，包括代表性不足的少数民族，提供生物化学、显微镜、遗传学和分子生物学方面的跨学科培训。

Arsenic is a naturally occurring, toxic metalloid that is known to cause cancers if consumed. Arsenic contamination of soils and water is an environmental problem in many regions of the world, including the US. This research focuses on the fern Pteris vittata, which is remarkable because it and its close relatives are the only known multicellular organisms that are able to tolerate and accumulate very high levels of arsenic. The goals of this research are to understand how this plant is able to take up and store this toxin without succumbing to its deadly effects. Two genes isolated from this plant are hypothesized to be involved in this process. One is an arsenate reductase, which reduces the arsenate, which is taken up from the soil by the root, to arsenite. The other is an arsenite effluxer that is hypothesized to move arsenite into the vacuole of the cell where it is safely sequestered. One goal of this research is to express these genes in another arsenic-sensitive plant (Arabidopsis thaliana) to see if they are able to confer arsenic tolerance to other plants. A second goal is to localize the proteins produced by these genes at the tissue, cellular and subcellular levels in P. vittata. The final goal is to develop basic genomic tools for P. vittata that ultimately will allow us to identify other genes that are involved in arsenic tolerance and hyperaccumulation in this plant. This research has broader impacts in that it will identify a mechanism of arsenic tolerance and accumulation that may be of practical value in the remediation of arsenic contaminated soils. This research also will provide undergraduate and graduate students, including underrepresented minorities, interdisciplinary training in biochemistry, microscopy, genetics and molecular biology.