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Full crop protection from an insect pest by expression of long double-stranded RNAs in plastids

Science  27 Feb 2015:
Vol. 347, Issue 6225, pp. 991-994
DOI: 10.1126/science.1261680

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Bypassing a plant's defense for pest defense

Colorado potato beetles can skeletonize the leaves on a potato plant, devastating crop yields. Insecticides are increasingly useless as the beetle evolves resistance. Zhang et al. used RNA interference to take down this beetle (see the Perspective by Whyard). Success required shifting production of the double-stranded RNA to the plastids to evade the plant's own RNA management mechanisms. The insect's own RNA interference mechanisms then inactivated two everyday genes that the beetle can't do without.

Science, this issue p. 991; see also p. 950

Abstract

Double-stranded RNAs (dsRNAs) targeted against essential genes can trigger a lethal RNA interference (RNAi) response in insect pests. The application of this concept in plant protection is hampered by the presence of an endogenous plant RNAi pathway that processes dsRNAs into short interfering RNAs. We found that long dsRNAs can be stably produced in chloroplasts, a cellular compartment that appears to lack an RNAi machinery. When expressed from the chloroplast genome, dsRNAs accumulated to as much as 0.4% of the total cellular RNA. Transplastomic potato plants producing dsRNAs targeted against the β-actin gene of the Colorado potato beetle, a notorious agricultural pest, were protected from herbivory and were lethal to its larvae. Thus, chloroplast expression of long dsRNAs can provide crop protection without chemical pesticides.

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