Rooting out a poison

CASSAVA, the staple crop of over 500 millionpeople across rural Africa, Asia allAmerica can prove to be fatal if noproperly. But researchers working theUniversity of Newcastle in UK hopeprovide farmers with genetically safer varieties of the crop (New Scientists147, No 1995).

Cassava root contains poisoin in theform of cyanoglucoside. Its antidotenzymes are found in the latex. In a livingplant, the poison and the enzymessontact, to the plant has to beA before it can be consumed.processing method involves thelo o( cells. This permits theLit rglst on the pol111hanigglucoside. con- FlUAInto hydrogen?hgg root is rendered safe to eat when divested.

If any of the existing 184N brelakdowncompletion,ONIngead even 0 frequently appliedW in which naturally11 down the cellto act on the collision.

resserch team biochemist Monica Hughes, this fermentation process can be improved by usingnewly cloned genes. Hughes plans tomanufacture the cyanoglucoside-destroying enzymes using geneticengineering on natural bacteria obtained from the fermentation processing unitsin Africa.

The other strategyinvolves a long-term solution. By providing the rootswith larger doses of theenzyme, detoxification during fermentation can beimproved. Once the genes inthe plants are altered, iti would be possible for theplants to manufacture more enzymes inthe roots than before, Says Hughes, "Theplant is propagated vegetatively just byreplanting sticks, so we only need tomodify one plant and give it back to thefarmers".