Plant host-mediated RNAi technology has great potential for the control of plant Coleoptera and Lepidoptera pests. Using the host plant to express the dsRNAs directly target insect funcational genes, the resulted high expressed dsRNAs can be absorbed into the body by phytophagous insects, and then induce the system RNAi response, and thus successfully interfere with the expression of target genes to achieve insecticidal purposes. To excavate the ideal RNAi target gene and apply it to plant insect breeding is the current key issues.
A recent study by Dr. ZHU Zhen’s group at the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), in collaboration with Dr. ZHANG Tianzhen’s group at Nanjing Agricultural University, Dr. Tabashnik E. Bruce’s group at University of Arizona demonstrated novel insect-resistant cottons that pyramid RNAi and Bacillus thuringiensis (Bt).
Based on a large number of RNAi target screening, the key genes controlling of insect JH metabolism were selected as the best targets. The RNAi transgenic cotton showed a significant insect resistance, especially for the Bt-tolerant Helicoverpa armigera. The study further showed that the dsRNA cassettes were successfully expressed in RNAi cotton, and the mRNA levels of the target gene in the tested insects was significantly decreased, followed the synthesis of juvenile hormone was significantly reduced. Notably, pyramiding RNAi and Bt further enhanced the insecicidal activity. In addition, the analysis of multi-year insect resistance data showed that the RNAi cotton can delay the production of cotton bollworm resistance.
These findings suggest that RNAi cotton and RNAi + Bt cotton can overcome the problem that cotton bollworm is resistant to single strategy transgenic cotton, and it is the next generation of insect-resistant crops R & D laid the foundation.
This work entitled "Next generation transgenic cotton: pyramiding RNAi and Bt counters insect resistance" was published in Plant Biotechnology Journal
(DOI: 10.1111 / pbi.12709
This work was supported by grants from the Ministry of Agriculture of China, the Ministry of Science and Technology of China, and USDA Biotechnology Risk Assessment Grant Award.
Figure. To counter rapidly increasing pest resistance to transgenic crops producing single Bacillus thuringiensis (Bt) toxins, transgenic plant “pyramids” producing Bt toxin and RNA interference (RNAi) was developed. (Image by IGDB)
Dr. ZHU Zhen