According to the World Health Organization, cadmium can damage human kidneys and other organs. High doses of cadmium are debilitating.

Cadmium also can be toxic to plant tissue, but plants generally find ways to detoxify the heavy metal before it causes damage.

In research published in the journal Plant Physiology, Goldsbrough and his Australian collaborators described a mutant strain of Arabidopsis thaliana (a plant in the mustard family, often used in laboratory testing) that can't defend itself against cadmium. Then they figured out why it was so susceptible to cadmium poisoning.

"Normal Arabidopsis plants protect themselves by linking the toxic metal to a peptide once it's inside the plant," Goldsbrough says. The bound, nontoxic form of cadmium then gets dumped into a cell vacuole, a sort of bubble inside a cell that cordons off a section and holds the toxins at bay.

The mutant plants lacked the peptides that tie up and detoxify the heavy metal.

In subsequent related research, Goldsbrough and Purdue co-workers identified genes in Arabidopsis for other peptides that can bind and detoxify toxic metals.

The DNA that Goldsbrough has identified could be manipulated to produce plants able to mine large quantities toxic metals from soil. And what he's learned about Arabidopsis could be applied to other plants. Once breeders develop metal-mining plants, EPA Superfund-site farmers might clean up contaminated sites after a few cropping seasons.

The same DNA responsible for a plant's ability to pull toxic metals from soil could be manipulated to coerce carrot, corn, apple or rutabaga roots to reject heavy metals, Goldsbrough says. If grown in areas where soil is contaminated, such bioengineered fruits and vegetables would hold fewer toxins,
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Contact: Rebecca Goetz
rjg@aes.purdue.edu
765-494-0461
Purdue University
11-Apr-1997