title: Environmental RNAi in herbivorous insects.
abstract: Environmental RNAi (eRNAi) is a sequence-specific regulation of endogenous gene expression in a receptive organism by exogenous double-stranded RNA (dsRNA). Although demonstrated under artificial dietary conditions and via transgenic plant presentations in several herbivorous insects, the magnitude and consequence of exogenous dsRNA uptake and the role of eRNAi remains unknown under natural insect living conditions. Our analysis of coleopteran insects sensitive to eRNAi fed on wild-type plants revealed uptake of plant endogenous long dsRNAs, but not small RNAs. Subsequently, the dsRNAs were processed into 21 nt siRNAs by insects and accumulated in high quantities in insect cells. No accumulation of host plant-derived siRNAs was observed in lepidopteran larvae that are recalcitrant to eRNAi. Stability of ingested dsRNA in coleopteran larval gut followed by uptake and transport from the gut to distal tissues appeared to be enabling factors for eRNAi. Although a relatively large number of distinct coleopteran insect-processed plant-derived siRNAs had sequence complementarity to insect transcripts, the vast majority of the siRNAs were present in relatively low abundance, and RNA-seq analysis did not detect a significant effect of plant-derived siRNAs on insect transcriptome. In summary, we observed a broad genome-wide uptake of plant endogenous dsRNA and subsequent processing of ingested dsRNA into 21 nt siRNAs in eRNAi-sensitive insects under natural feeding conditions. In addition to dsRNA stability in gut lumen and uptake, dosage of siRNAs targeting a given insect transcript is likely an important factor in order to achieve measurable eRNAi-based regulation in eRNAi-competent insects that lack an apparent silencing amplification mechanism.
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Sergey
authors: S
authors: Ivashuta
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Yuanji
authors: Y
authors: Zhang
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: B Elizabeth
authors: BE
authors: Wiggins
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Partha
authors: P
authors: Ramaseshadri
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Gerrit C
authors: GC
authors: Segers
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Steven
authors: S
authors: Johnson
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Steve E
authors: SE
authors: Meyer
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Randy A
authors: RA
authors: Kerstetter
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Brian C
authors: BC
authors: McNulty
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Renata
authors: R
authors: Bolognesi
authors: Chesterfield Village Research Center, Monsanto Company, Chesterfield, Missouri 63017, USA.
authors: Gregory R
authors: GR
authors: Heck
mesh_terms: D000818:Animals; D004777:Environment; D059647:Gene-Environment Interaction; D060434:Herbivory / Q000235:genetics*; D007313:Insecta / Q000235:genetics* / Q000378:metabolism; D007814:Larva; D018517:Plant Roots / Q000469:parasitology; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D059467:Transcriptome; D003313:Zea mays / Q000469:parasitology
chemical_list: D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering
keywords: RNAi; corn rootworm; dsRNA uptake; eRNAi; siRNAs