Scientists figure out how rice absorbs arsenic 6-9-08

LONDON (Reuters) - Scientists have worked out how crops such as rice absorb arsenic, a finding that could help prevent people from eating dangerous levels of the poisonous metal, they said on Tuesday.

The same gene that helps plants fight off fungal infections appears to allow plant cells to absorb arsenite -- the damaging form of the metal, a Swedish and Danish team found.

"Our observations ... may provide a key to the development of low arsenic crops for food production," the team from the University of Copenhagen in Denmark and the University of Gothenburg in Sweden wrote in the journal BioMed Central Biology.

Arsenic, a common and naturally occurring element, can build up in plants or in the bodies of animals and people to cause lung disease and cancers, even long after exposure.

Contaminated water is the main source of arsenic poisoning followed by arsenic-rich food, especially rice that has been irrigated with water contaminated by the metal, the researchers said.

Tens of millions of people in dozens of countries in the developing and developed world drink unsafe water containing arsenic levels above World Health Organization guidelines, according to research presented last year at the Royal Geographical Meeting in London.

The Scandinavian team injected yeast with the rice version of the gene that controls how cells absorb arsenite and then compared what happened in yeast without the product of this gene, called nodulin26-like intrinsic protein.

Yeast with these "transporter" proteins accumulated arsenite while the others did not, said Thomas Jahn, a plant researcher at the University of Copenhagen who led the study.

"This is the genetic proof," Jahn said in a telephone interview.

This same gene also plays a protective role by allowing crops to absorb silicon in cell walls as a defense against fungal infections, he added.

The findings could one day lead to genetically engineered crops that allow rice, for example, to accumulate silicon but not arsenic, Jahn said.

"The plant is not able to discriminate between these very similar compounds -- one of which is extremely toxic and the other which is extremely important for life," he said.

Comment:

We have always known this an often suggest Bella Mira Rice Plus along with any heavy metal detoxification program.