China
November 194 2007
Chinese
Academy of Sciences (CAS) plant physiologists have recently
invented a plant-mediated RNA interference (RNAi) technique to
effectively and specifically control the gene expression of the
cotton bollworm (Helicoverpa armigera) and stunt its growth.
Experts say that the feat marks a research breakthrough in the
field of biotechnology for plant insect resistance, offering a
novel strategy to fight plant pests.
Cotton is a staple cash crop in China. Its nation-wide planted
acreage could reach up to seven million hectares, accounting for
20% of the world total. But cotton pest is a serious problem for
the trade. The cotton bollworm, for instance, could cause losses
as much as several hundreds of million dollars a year.
To fight against the pest, researches have developed strains of
the anti-pest cotton using genetic modification, for instance,
inserting Bacillus thuringiensis (Bt) gene to produce toxins.
However, the approach has become less effective in recent years
as the cotton bollworm has developed resistance against the
toxins.
Now a research team led by Prof. CHEN Xiaoya from the Institute
of Plant Physiology and Ecology under the CAS Shanghai
Institutes of Biological Sciences has come up with new
techniques. As reported in 4 November issue of
Nature
Biotechnology, the researches have first identified an enzyme
named CYP6AE14 from cotton bollworm, which permits this
herbivore to tolerate otherwise inhibitory concentrations of the
cotton metabolite, gossypol. The enzyme is highly expressed in
the midgut and its expression correlates with larval growth when
gossypol is included in the diet.
The researchers discovered that RNA interference occurs when
larvae are fed plant material expressing double-stranded RNA
(dsRNA) specific to CYP6AE14 as the dsRNA bind to the target
sequence of CYP6AE14, decrease the levels of this transcript in
the midgut and retard larval growth.
Experts say that feeding insects with plant material expressing
dsRNA may be a general strategy to trigger RNAi and could find
applications in entomological research and field control of
insect pests other than the cotton bollworm. RNAi could be a new
and easy way to fight plant pests. |
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