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A milestone in transgenic plant resistant to insect

The research group led by Prof. Xiao-Ya Chen has discovered a new method to protect plants from insect attack. This work was just released in Nature Biotechnology Advance Online Publication. Prof. Xiao-Ya Chen, an Academician of Chinese Academy of Sciences at the National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, together with Dr. Ying-Bo Mao, the first author of the article, engineered Arabidopsis and tobacco plants to produce small RNAs targeting specific insect genes of cotton bollworm (Helicoverpa armigera), and then fed the insect with these plants and monitored the targeted genes expression. They have tested this technology with several genes in cotton bollworm. Study of a P450 gene isolated from cotton bollworm was suggested that it might be involved in cotton toxin (gossypol) detoxification. Generally, cotton bollworm can live with the diet containing gossypol. However, when the worm was fed with the plants producing dsRNA against the P450 gene, its expression was down-regulated and the worm was severely stunted or even deceased. The research group is now applying the technology on the transgenic cotton, which is the natural host for cotton bollworm. The new discovery not only develops new tool for insect functional genomics research but also provides a new approach of controlling herbivores. Another Nature Biotechnology article from James Roberts′s group in Monsanto Company also reported the similar findings on coleopteran insects obtained from maize.

《Nature》gave a high light on these works: h;An important advantage of this approach over the current alternatives is that the interfering RNA could probably be made to target pests very selectively. This could satisfy concerns about insecticides indiscriminately killing key links in the food chainh;.

RNA interference is a newly-discovered mechanism of gene expression regulation, which is widely used in basic research and holds great potentials in human disease therapy. There are a large amount of small RNA molecules (~20 nt) in plant cells. Except for a small fraction with target genes identified, the function of most plant small RNAs remains in the dark. The technology created by Prof. Chen′s group suggests a new role of plant small RNAs fighting again insects.

Cotton is a main economic crop in China. About five million hectares are cultivated per year in China, which account for ~13% of the world total. In China, there are more than three hundred million farmers relying on cotton cultivation and over ten million workers in textile industry. The export of textile products from China values more than fifty billion US dollars each year. The cotton production in China has been impacted by different cotton pests and pathogens. The cotton bollworm alone, in China, can cause a loss of several billion RMB annually, or even more than ten billion RMB in some years.

Transgenic cotton resistant to the bollworm has been developed from 1980s. Bt-toxins are a class of chemicals that specifically target caterpillars and are naturally produced by the bacterium Bacillus thuringiensis. Genetically engineered cotton producing the toxins could be resistant to herbivore insects and has been commercially grown for decades. However, Bt-resistant insects have been noticed in pest population in recent years and alternative strategy to develop transgenic pest-resistant crops is a great need. The discovery by Prof. Chen′s group might shed new light on designing a novel type of pesticides.
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