Plant-mediated RNAi for aphid control could be a significant tool in the near future and Yu et al. review efforts to date to apply RNAi to aphids as part of an effort to see where we are and what challenges remain. The phloem feeding habits of aphids present a number of challenges that Yu et al. suggest can be met with some specific plant engineering solutions.
The authors review some of the basics of RNA interference and its application in insects including a general discussion of the problem of target-gene and target-sequence selection, the design of the RNAi construct and its delivery in order to yield sufficient amounts of dsRNA.
Yu et al. provide a comprehensive compilation of published research on RNA interference in aphids and organize this information in two tables. The first reports the species, target gene, method of dsRNA or siRNA delivery (feeding or injection) and the concentrations used, along with a short description of the experimental outcomes.The second table includes only studies involving plant-mediated RNAi. Seven of the nine studies referenced involved the use of Myzus persicae feeding on transgenic tobacco or Arabidopsis and targeting a variety of genes. All of those studies reported some negative impact on the fecundity of insects feeding on these plants.
Finally, the authors address challenges facing the successful implementation and adoption of plant-mediated RNAi for aphid control. A notable challenge is the presence of dsRNAases in the gut of at least the pea aphid. Furthermore, the authors note that interactions between the aphid’s RNA interference machinery and the plant viruses they transmit could impact the RNAi response to plant-mediated RNAi and this is one of a number of areas that needs further study.
Producing dsRNA and delivering it to the phloem is a challenge and will benefit from the use of phloem-specific promoters and enhancers, according to the authors. Of course, the potential for off-target effects and the development of aphid resistance are also of serious concern.
Overall, the authors present a balanced review of this important topic and while presenting the state of the art they also make very clear the numerous challenges that remain.
Yu, X.-D., Liu, Z.-C., Huang, S.-L., Chen, Z.-Q., Sun, Y.-W., Duan, P.-F., Ma, Y.-Z. and Xia, L.-Q. (2016), RNAi-mediated plant protection against aphids. Pest. Manag. Sci., 72: 1090–1098. doi:10.1002/ps.4258