Detoxifying soils that are contaminated with arsenic has always been difficult to achieve with human hands and instruments. However, the introduction of genetically modified plants may be able to reduce arsenic levels with much greater ease.

The gene of interest comes from the fern Pteris vittata, a plant that is 100 to 1000 times more resistant to arsenic than other species of plants. Jody Banks and David Salt, professors at Purdue University, determined the resistant genes by using yeast functional complementation. Essentially, they introduced thousands of different genes from the fern (since the fern’s genome was not sequenced) into yeast, which was not resistant to arsenic, and then exposed the yeast to arsenic. Yeast that survived had taken up the genes necessary for arsenic tolerance.

To validate the results found via yeast functional complementation, the researchers knocked out the resistance genes in fern plants and then exposed the plant to arsenic. With knocked out genes, the plant was unable to survive. The genes that Banks and Salt discovered are not present in flowering plants, but careful genetic modification of flowering plants could lead to arsenic resistance in flowering species (e.g. crop plants) as well.

Since the activity of the genes leads to the absorption of arsenic from the soil, plants with these genes could remove arsenic from polluted lands. After the fern absorbs the arsenic, it relocates the arsenic to vacuoles in its fronds, where the arsenic can do little to damage the plant or its surroundings.

Discussion Question: Do you think that arsenic-tolerance genes can be expressed similarly in flowering plants? What would be the advantage?

News Article: http://www.sciencedaily.com/releases/2010/06/100608183044.htm

Journal Article: http://www.plantcell.org/cgi/content/abstract/tpc.109.069773v1