Persistence and transgenerational effect of plant-mediated RNAi in aphids.
Bottom Line: Moreover, gene expression levels returned to wild-type levels within ~6 d after removal of the aphids from the transgenic plants, indicating that a continuous supply of dsRNA is required to maintain the RNAi effect.Target genes were also down-regulated in nymphs born from mothers exposed to dsRNA-producing transgenic plants, and the RNAi effect lasted twice as long (12-14 d) in these nymphs.In a field setting, a reduction of the aphid reproduction by 40-60% would dramatically decrease aphid population growth, contributing to a substantial reduction in agricultural losses.
Affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.Show MeSH
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Mentions: It was previously shown that plant-mediated RNAi of Rack1, MpPIntO2, and MpC002 resulted in decreased aphid fecundity by ~10–20% at 16 d (Pitino et al., 2011; Pitino and Hogenhout, 2013). Given that the RNAi effect is transferred to GPA progeny, it was hypothesized that the negative impact on fecundity of RNAi may be higher over several GPA generations. To test this, 0- to 2-day-old nymphs were seeded at one nymph per plant on four of each of the dsRack1, dsGFP, dsMpC002, and dsMpPIntO2 transgenic A. thaliana plants. The total numbers of adults and progeny were counted at 2, 3, and 4 weeks post-GPA inoculation (constituting about three generations of aphids). Total aphid numbers slowly declined over 4 weeks and reached a 30–40% reduction on dsMpPInt02 and dsRack1 plants and up to 60% on dsMpC002 plants compared with dsGFP plants (Fig. 4). DsRack1, dsMpC002, and dsMpPInt02 treatments all resulted in a significant reduction in the aphid population at 4 weeks (Student’s t-test, n=4, P<0.0009). Only dsMpC002 resulted in a significant reduction in population size by week 3 (Student’s t-test, n=4, P=0.011). Thus, the RNAi-mediated down-regulation of GPA genes reduces GPA fecundity over several generations and can further reduce the exponential growth of aphid populations over a longer time frame (Fig. 4). Plant-mediated RNAi of MpC002 is more effective at reducing the GPA population than that of Rack1 and MpPIntO2.
Affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.