Comparison of RNAi sequences in insect-resistant plants to expressed sequences of a beneficial lady beetle: a closer look at RNAi off-target considerations

Authors: Allen, Margaret - Meg

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2017
Publication Date: 3/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5661727
Citation: Allen, M.L. 2017. Comparison of RNAi sequences in insect-resistant plants to expressed sequences of a beneficial lady beetle: a closer look at RNAi off-target considerations. Insects. 8:1-11.

Interpretive Summary: A new technology called RNA interference (RNAi) is being implemented in major crops, beginning with maize or corn. This technology interferes with vital insect genes by incorporating double stranded RNA into plants. The technology is based on gene sequences that are unique to the target insect, but some possibility for effects on closely related insects is still possible. To examine some proposed insect target genes, gene sequences from a beneficial insect, the lady beetle Coleomegilla maculata were compared to a gene sequence from western corn rootworm, a gene from the Colorado potato beetle, and some genes from the red flour beetle, a genetic model organism. Some regions of high similarity were identified in the potato beetle and flour beetle gene sequences, suggesting that these sequences should be examined more closely before implementing RNAi technology in potato and other crops.

Technical Abstract: Sequences obtained from transcriptomes of the lady beetle Coleomegilla maculata were compared to those designed for incorporation into crops. Searches of the transcriptomes identified sequences as the most likely to be closely similar to the sequences described in RNAi plant incorporated products. Some proposed prime RNAi pest management targets were also used to identify predicted orthologs from C. maculata. The lady beetle sequences were aligned with sequences from corn rootworms and Colorado potato beetles and, as appropriate in the case of targets, regions of similarity were compared with the genetic model organism for beetles, Tribolium castaneum. Some high levels of nucleotide identity were identified, particularly with an actin-derived sequence from Colorado potato beetle.