As well as brightening your room, potted plants may one day help to prevent
headaches in "sick" houses by absorbing toxic gas, according to Japanese
scientists.
Researchers have genetically engineered plants that can absorb formaldehyde,
a pungent chemical compound used as adhesive in building materials and
furnishing, one of the researchers said Tuesday.

Formaldehyde is seen as a major factor in what is known as sick-house
syndrome -- headaches, dizziness and other health problems triggered by
chemical substances in the home.

"We expect the plants to absorb it steadily" along with carbon dioxide for
photosynthesis, said Katsura Izui, a professor of molecular plant physiology
at Kinki University in western Japan.

The plants have two kinds of genes imported from micro-organisms known as
methylotrophs, which use formaldehyde for their growth.

One host plant was tobacco and the other was thale cress, a small plant
formally called Arabidopsis, which has a short life span of two months and
is widely used as a model plant in biology.

Izui said the amount of formaldehyde absorbed by the plants was small
compared with the carbon dioxide they use.

But the study showed that modified Arabidopsis survived four weeks in boxes
dense with formaldehyde with the level of toxic gas falling to some
one-tenth of the original level.

All wild Arabidopsis died in the same circumstances. Similar results were
also obtained with experiments using modified tobacco plants, he said.

Izui said the density drop may have also stemmed from absorption by the agar
used as a substitute for soil in the experiment boxes because formaldehyde
is highly soluble in water.

"We are now trying to make new devices for more precise observation," he
said, adding they were trying to apply the technology in common foliage
plants.

The study was conducted jointly with Professor Yasuyoshi Sakai, an expert on
micro-organisms at Kyoto University.
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