Project Description

“Nearly 108 countries of the globe [are] affected by arsenic contamination in groundwater.”[1] Arsenic or As is a versatile metal found on the periodic table with the atomic number 33. It is found in the earth’s crust and widely distributed throughout the water, air, and land. Arsenic is used in various industries, but exposure to arsenic, especially inorganic arsenic, can lead to health problems or even death in many organisms. Exposure to arsenic can cause harm to the eyes, skin, liver, and other organs; and long-term exposure can lead to a possibility of cancer(s) and even death. For most of the world, contaminated water and food are the main causes for arsenic poisoning. High amounts of arsenic found in soil can accumulate into crops, but arsenic is known to hyperaccumulate in rice crops. It also has negative effects on the plant in general, which can lead to losses in crops and less food produced. Rice “is a food staple for more than 3.5 billion people around the world,” and arsenic poisoning can affect about half the world.[4] Because rice is a large part of the diets of many people across the world, it was important to learn more about mechanisms and proteins that could potentially increase the arsenic tolerance of rice and other crops.

Our interest in arsenic began after we found articles about arsenic biomagnification and arsenic contaminated water. As we are a San Diego based team, contaminated water and biomagnification are major concerns for us and the marine ecosystem that is right next door. As we dug deeper into our research on arsenic, we found arsenic also poses a threat on our food crops. Our interest in doing a project on arsenic was piqued when we learned about arsenic accumulation in rice, considering how rice is an important food crop. We wanted to find a way to reduce arsenic poisoning from crops and prevent plants from being affected by arsenic-contaminated soil. We were not sure how we would go about this until we came across articles about an arsenic-tolerant fern.

According to the book Plant Physiology, “The arsenic hyperaccumulating fern P. vittata is an unprecedented system for the study of arsenic metabolism and the evolution of arsenic tolerance and resistance mechanisms in plants and other multicellular organisms.” [3] Pteris Vittata, also known as the Chinese Ladder Brake Fern, is a plant that accumulates arsenic in high amounts. It is native to China but is found in various areas of the US, including California. The fern’s mechanisms make it able to tolerate high amounts of arsenic, which would usually kill other plants and organisms. There are many proteins inside the Pteris Vittata that contribute to its high tolerance to arsenic. Our group decided to focus on three proteins that work together to maintain arsenic tolerance in the plant. The three proteins we chose are PvPht1;3, PvACR2, & PvACR3. PvPht1;3 is a phosphate transporter, PvACR2 is an arsenate reductase, and PvACR3 is an antiporter. These three proteins work together to help Pteris Vittata sustain the high amount of arsenic that it is able to.

Our team has decided to model the three proteins using Michaelis-Menten kinetics to help us further understand how the mechanisms of these proteins are able to provide such high arsenic tolerance. By using these models and the research we have gained, we can use this plant to provide a solution to the problems caused by arsenic. We believe that we can put the arsenic resistance mechanisms of Pteris Vittata into other plants to allow higher arsenic tolerance in plants. Research with other plants such as Arabidopsis Thaliana(Thale Cress), rice crops, and tobacco crops has shown that they are able to also tolerate high amounts of arsenic. Although placing arsenic tolerant mechanisms in crops that are planted for consumption isn’t ideal, placing these mechanisms in other plants can help the plants with arsenic tolerance while also doing phytoremediation. Certain parts of the world have extremely high amounts of arsenic which cause a lot of harm to the people and their crops, hindering them from living a safer life. By placing Pteris Vittata or plants that have the fern’s arsenic tolerant mechanisms in these areas, will help purify the soil by removing the arsenic. According to PNAS, expermination with ferns in areas filled with arsenic have been and show that “the ferns extracted arsenic over the course of their growing season,[for] about five months…leaving purified soil in place.”[2] Pteris Vittata’s systems can help lead to new discoveries on arsenic tolerant mechanisms, helping reduce arsenic poisoning around the world.

Sources

[1] Arsenic contamination of groundwater: A global synopsis with focus on the Indian Peninsula. (n.d.). Geoscience Frontiers, 12(3). https://doi.org/10.1016/j.gsf.2020.08.015

[2] Beans, C. (2017, July 18). Phytoremediation advances in the lab but lags in the field. https://www.pnas.org/doi/10.1073/pnas.1707883114

[3] Ellis, Gumaelius, Indriolo, Pickering, Banks, & Salt. (2006). A Novel Arsenate Reductase from the Arsenic Hyperaccumulating Fern Pteris vittata. Plant Physiology, 141(4), 1544–1554. https://doi.org/10.1104/pp.106.084079

[4] Food staple. (n.d.). National Geographic Society. Retrieved October 9, 2022, from https://education.nationalgeographic.org/resource/food-staple

[5] WHO, W. H. O. (2018, February 15). Arsenic. World Health Organization: WHO. https://www.who.int/news-room/fact-sheets/detail/arsenic