Rooting out a poison

-- CASSAVA, the staple crop of over 500 million
people across rural Africa, Asia all
America can prove to be fatal if no
properly. But researchers working the
University of Newcastle in UK hope
provide farmers with genetically safer varieties of the crop (New Scientists
147, No 1995).

Cassava root contains poisoin in the
form of cyanoglucoside. Its antidot
enzymes are found in the latex. In a living
plant, the poison and the enzymes
sontact, to the plant has to be
A before it can be consumed.
processing method involves the
lo o( cells. This permits the
Lit rglst on the pol
111hanigglucoside. con- FlUA
Into hydrogen
?hgg root is rendered safe to eat when divested.

If any of the existing 184
N brelakdown
completion,
ON
Ing
ead even
0 frequently applied
W in which naturally
11 down the cell
to act on the collision.

resserch team biochemist Monica Hughes, this fermentation process can be improved by using
newly cloned genes. Hughes plans to
manufacture the cyanoglucoside-destroying enzymes using genetic
engineering on natural bacteria obtained from the fermentation processing units
in Africa.

The other strategy
involves a long-term solution. By providing the roots
with larger doses of the
enzyme, detoxification during fermentation can be
improved. Once the genes in
the plants are altered, it
i would be possible for the
plants to manufacture more enzymes in
the roots than before, Says Hughes, "The
plant is propagated vegetatively just by
replanting sticks, so we only need to
modify one plant and give it back to the
farmers".