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RNAi for pest control: Will it replace the Bt gene ?
November 5, 2007
molbioandbiotech
Transgenic
plants expressing Bt gene have been widely used for pest control for
the past several years. However, due to certain limitations associated
with using this technology scientists have been looking for
alternatives, and they found one in RNAi. The researchers at the
Chinese Academy of Sciences, Shanghai, and at Monsanto and Devgen, a
Belgian company have shown for the first time that RNAi could be used
as an efficient means of pest control. In two independent studies, when
scientists fed the insect larvae with the plant material expressing
dsRNA for the insect genes, it was found that it triggered the RNAi
pathway in insect larvae and blocked the expression those genes.
In the first study, cotton bollworm (Helicoverpa armigera) was the target. dsRNA for a cotton bollworm cytochrome P450 gene, CYP6AE14,
was made to express in the plants. This plant material was then fed to
the insect larvae, and it was found that the levels of the cytochrome
P450 transcript in the larval midgut decreased and larval growth
retarded. This cytochrome P450 gene permits Helicoverpa armigera
to tolerate inhibitory concentrations of the cotton metabolite,
gossypol, and survive. In the absence of this gene, the insect showed
decline in its growth.