Bio-technology.

A Danish company, Aresa Biodetection, has developed genetically-modified flowers that change color when their roots come in contact with nitrogen dioxide in the soil. Explosives used in mines produce N[O.sub.2] as the chemicals gradually decay. Aresa's invention, based on research at the institute of Molecular Biology at Copenhagen University, uses a plant's normal reaction to turn red or brown when subjected to stressful conditions such as cold or drought, but has genetically coded it to react only to nitrogen dioxide. The biodetection system is currently being developed using the plant Arabidopsis thaliana (Thale or mouse cress). The genetically engineered plants are modified in a way that only allows these plants to go red if triggered by a specific stimulus present in the soil. Such stimuli trigger the production of a key enzyme in the biochemical pathway responsible for production of the group of red pigments called anthocyanins. The resulting color change is expected within 3-6 weeks, dependent on the growth conditions. There are many reasons for selecting Arabidopsis thaliana as a first choice for development of the system:

1. The plant has a fast growth rate (growth cycle of 6-8 weeks).

2. The plant is naturally growing all around the world (except from the poles)

3. The plant is a well-studied genetic model system; thus, complete data are available.

4. Since the plant is an obligate self-pollinating plant, one can avoid spreading of genetically engineered plants to the environment. Male-sterility can be introduced into the genetically engineered plants in order to eliminate the risk for spreading pollen. Thus, the plants developed by Aresa neither germinate nor set seeds unless a specific growth hormone is added to the plants, so plant growth can be strictly controlled. Carefully restricted field tests begin this year, and actual use could happen within the next couple of years.

Circle 106--Aresa Biodetection, or connect directly to their website at www.rsleads.com/403dt-106