Host-induced silencing of MpPar6 confers Myzus persicae resistance in transgenic rape plants

Plant-mediated RNA interference (RNAi) has emerged as a promising technology for insect control. The green peach aphid, Myzus persicae, feeds on over 400 species of host plants. Brassica napus (rape) is the second most important oilseed crop worldwide. Myzus persicae is highly reproductive and causes severe damage to the rape plants due to its quite flexible life cycle. In this study, we tested the RNAi effects of transgenic rape plants on M. persicae. By in vitro feeding M. persicae with artificial diets containing double-stranded RNAs (dsRNAs) targeting seven aphid genes, we identified a new gene encoding the partitioning-defective protein 6 (Par6) as the most potent RNAi target. Tissue- and stage-expression analysis of Par6 suggested this gene is highly expressed in the embryo and adult stage of M. persicae. We next generated transgenic rape plants expressing dsPar6 by Agrobacteriummediated transformation and obtained nine independent transgenic lines. Compared to wild-type control plants, transgenic rape lines expressing dsPar6 showed strong resistance to M. persicae. Feeding assays revealed that feeding transgenic rape plants to M. persicae significantly decreased MpPar6 expression and survival rate and impaired fecundity. Furthermore, we showed that the resistance levels to M. persicae are positively correlated with dsPar6 expression levels in transgenic rape plants. Our study demonstrates that transgenic rape plants expressing dsPar6 are efficiently protected from M. persicae. Interfering with the genes involved in embryo development could be the effective RNAi targets for controlling aphids and potentially other insect pests.