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2-Plants: Scorpion gene gives plants a sting in their tail

-------------------------------- GENET-news -------------------------------

TITLE:  Scorpion gene gives plants a sting in their tail
SOURCE: SciDev.Net, UK, by Wagdy Sawahel
DATE:   1 Aug 2005

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Scorpion gene gives plants a sting in their tail

Chinese scientists have inserted scorpion and moth genes into oilseed
rape (canola) plants to make them poisonous to insects feeding on them.

The researchers say that using two foreign genes at the same time means
insect pests will be less likely to develop resistance to the genetically
modified (GM) plants. The findings were published online in Plant Cell
Report on 19 July.

The researchers tested the GM plants by exposing them to caterpillars of
the diamondback moth (Plutella maculipenis). All of the plants showed
some defense against the caterpillars, although the extent of this varied
from plant to plant.

The caterpillars, which are major crop pests in parts of Africa, Asia and
Latin America, have developed resistance to several available pesticides.
There are also reports they are becoming resistant to 'Bt' plants, which
are genetically modified to produce a toxin that kills insects but is
harmless to birds and mammals.

The Chinese team, led by Jingxue Wang of the Agri-Biotechnology Research
Centre of Shanxi Province, inserted two genes at once to overcome this

The gene from the Asian scorpion (Buthus martensii) produces a poison
that specifically affects insect nervous systems, leading to paralysis.
The gene from the tobacco hawkmoth (Manduca sexta) produces a chemical
that breaks down chitin, a major component of insects' outer surface and
gut lining.

Because it is unlikely that a caterpillar would be able to resist both
toxins at once, the researchers say their approach could slow down and
minimise the chance of an insect developing resistance to the plants.

They also suggest using their approach in combination with the Bt toxin
genes already widely used.

Lead researcher Wang, told SciDev.Net the team is trying the same
combination of genes in GM cotton.

Eric Messens, a professor of plant molecular genetics at Flanders
Interuniversity Institute for Biotechnology at Ghent University, Belgium,
warns however that some scorpion toxins previously thought to affect only
insects can also affect mammals.

He told SciDev.Net that detailed studies must be conducted to see whether
the toxins produced by the GM plants affect human health.

Another concern about GM oilseed rape is that insects or the wind could
carry pollen with foreign genes into non-GM oilseed rape crops or related

"Discussions about biosafety should be based on the results of practical
case studies and not on worst case scenarios," says Gerhard Schwarz, a
researcher at the Germany-based EpiGene company.

Schwarz and colleagues published a two-year field study of GM oilseed
rape online in the European Journal of Agronomy on 21 June.

The team found that genetic contamination of non-GM plants with GM genes
could be kept below the 0.9 per cent level required by European food
labelling rules, without limiting the distance between the two sets of crops.

"Our results showed that the gene flow by pollen dispersal can be brought
under control and does not lead to a biological catastrophe," Schwarz
told SciDev.Net.

GM crops can therefore co-exist with conventional and organic farming, he

Link to abstract of paper in Plant Cell Report

Reference: Plant Cell Report doi: 10.1007/s00299-005-0967-3

Link to abstract of paper in European Journal of Agronomy

Reference: European Journal of Agronomy doi: 10.1016/j.eja.2005.04.002


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