Characterization and Enhancement of a Natural RNAi-Based Defence Mechanism in Crop Plants Against Insect Herbivores

• Applicant: Dr. Doga Cedden
• Subject Area: Animal Physiology and Biochemistry ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 585515648

Plants cannot move, so they need to protect themselves against herbivory through other means, including physical barriers and chemical defences such as secondary metabolites. Although chemical and physical defence mechanisms are well characterized in plants, whether plants have also evolved nucleic acid-based mechanisms, such as RNA interference (RNAi), to defend themselves against insect herbivores remains unclear. Recently, artificial RNAi-based pest control approaches, including double-stranded RNA (dsRNA) spraying on crops and transgenic plants, have emerged as eco-friendly alternatives for managing certain pests, such as beetles. Plants are also known to naturally produce dsRNA. Taken together, these suggest plants may have evolved dsRNA loci that mediate natural RNAi-based defence against insects. My preliminary work identified a chloroplast-encoded natural dsRNA locus, dsNode343, in oilseed rape and suggested that dsNode343 is processed and initiates the RNAi pathway in the cabbage stem flea beetle, leading to insecticidal effects. The first aim of the project is to comprehensively characterize this potential natural RNAi-based defence mechanism by focusing on dsNode343 in two crop plants, oilseed rape and potato, against their insect pests, the cabbage stem flea beetle and the Colorado potato beetle, respectively. Specifically, the project will employ RNA-seq and functional assays to characterize the processing, transcript targets, and insecticidal effects of dsNode343 taken up from the host plant in the two insects, as well as the deployment of this natural dsRNA in the two plants. This aim has the potential to fill a significant gap in the field of plant–herbivore interactions and open a new line of research. The second aim is to provide proof of concept for a strategy to enhance the natural RNAi-based defence mechanism in crop plants. To that end, the project will focus on the sequence of the natural plant dsRNA, dsNode343, in oilseed rape and its homologous sequence in potato, and identify ways to improve insecticidal efficacy. This will be achieved through the development of a computational algorithm to efficiently increase the complementarity of the dsNode343 sequence to essential insect gene transcripts, followed by bioassay-based testing of dsNode343 sequence variants. The expected outcome of this aim is the establishment of a strategy for improving the natural RNAi-based defence mechanism via a few nucleotide modifications, in compliance with the EU’s NGT-1 proposal. Hence, the project has implications for producing commercial insect-resistant crop plants that could be cultivated in the EU.

• DFG Programme: Position