( n be harvested--and has the potential t...)Researchers discover way to transport environmental arsenic to plant leaves in new clean-up strategy

In research reported in 2002 in Nature Biotechnology, Meagher's team inserted two unrelated genes from the bacterium E. coli called arsC and ECS into Arabidopsis, a model lab plant and small member of the mustard family. This allowed the plants to resist the toxic effects of arsenic and sequester three-fold more arsenic in their shoots than normal plants. Still this was too ineffective to allow planting of the transgenic plants on arsenic-polluted sites, since far more arsenic needed to be moved into the plant leaves for safe harvesting and disposal.

In the just-reported research, the team identified a single gene, ACR2, in the Arabidopsis genome as one that allows the plants to move sequestered arsenic in roots. By engineering plant lines with a silenced ACR2 gene, they discovered they could get 16-fold more arsenic in shoots than in natural wild-type Arabidopsis. This experiment identified the active mechanism for sequestering arsenic in roots.

"We want a 35- to 50-fold increase in these plants' ability to sequester arsenic," said Meagher, "and now that we understand the mechanism, we believe that is possible." Indeed, it appears possible to create arsenic-eaters among tree, shrub and even grass species, using the new knowledge.

The problem of arsenic pollution is especially severe all over the Ganges River basin in India. During the so-called "Green Revolution" of the '60s and '70s, the cultivation of rice in flooded fields became pervasive, and workers dug open wells all over India through soil and rocks with naturally occurring arsenic. The result was widespread arsenic pollution from contaminated water. The problem is thus extremely widespread and not the result of industrial accidents or practices.