This Arsenic-Tolerant Fern Could Help Scientists Clean Toxic Waste

The Pteris vittata fern can accumulate and tolerate high levels of arsenic, making it an effective way to remediate contaminated soil and water. Agricultural Communication/Tom Campbell

A common houseplant may hold promise when it comes to cleaning up toxic environments. New research published in Current Biology finds that the plant species Pteris vittata, commonly known as a Chinese brake fern, has the ability to accumulate and tolerate high levels of arsenic that would otherwise kill other plants and animals. Such knowledge could prove useful in cleaning up toxic environments.

“Other researchers have shown that this fern, when grown on arsenic-contaminated soils, can remove almost 50 percent of the arsenic in five years,” said study author Jody Banks in a statement. “It takes time, but it’s cheap.”

Purdue University researchers sequenced the genomes of the fern to determine the genetic and cellular mechanisms that control how well it tolerates arsenic. Three genes, in particular, showed high activity when the plant came into contact with arsenic, allowing it to store the toxic element within its fronds without detrimental effects. A protein called GAPC1 "chemically traps" arsenate from the soil. In other plants, GAPC1 uses phosphate to breakdown glucose for energy, but in a Chinese brake fern, it has a higher affinity for arsenate than phosphate, which essentially neutralizes the effects of arsenic. GSTF then changes arsenate into arsenite (a form of arsenic that can be sequestered) through a process called arsenate reductase activity. 

“These and other genes work together to mop up arsenic inside a cell until it can be stuffed safely away in the cell’s vacuole where it can’t do any harm,” Banks said, adding that the ferns were observed hyperaccumulating more than 2 percent of their dry weight as free arsenite.

A similar biosynthesis ability has been demonstrated in a bacterium called Pseudomonas aeruginosa, whose nearly identical genetic mechanisms suggest the two evolved similar tolerance methods.

“This fern has co-opted the same mechanism to tolerate arsenic that bacteria use,” said researcher Chao Cai. “And it is the only eukaryote that can do this. No plant or animal that we know of can do it like this fern.”

Modifying other plants to have these same genetic tendencies may one day help remediate arsenic from contaminated soil in a quick and efficient way. As the researchers note, soil and groundwater contaminated with arsenic pose a potential threat to millions of Americans and hundreds of millions of people around the world. The toxic metalloid contaminates soil from natural and human-caused activities and poisons people when they drink contaminated water or eat crops grown in soil that has been exposed. Once inside human cells, it leads to cell death through oxidative stress or by interfering with the cell’s ability to produce ATP, a molecule needed to provide energy to cells.

Purdue University researchers have determined the genetic mechanisms that allow the fern to withstand arsenic, which could lead to the modification of other plants that could remediate contamination even more quickly and efficiently. Agricultural Communication/Tom Campbell

 

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