Agricultural pests are the main plant pathogens, posing serious threats to the staple crops. In recent years host-induced gene silencing (HIGS) has been produced as a new type of pathogen control strategy, and the HIGS genetic transformation has been reported as a commercial application in the prevention and control of pests. Given the dominance of lepidopterid insects among agricultural pests and the low efficiency of RNAi in lepidopterid insects, the efficiency of HIGS control calls for an urgent solution. Mythimnaseparata walker, an insect of the noctuidae family of the lepidopterid order, is one of the main pests of corn and other gramineous crops, characterized by being migratory, gluttonous and omnivorous. Its outbursts are occasionally witnessed in the areas between the Yangtze River and the Huai River, the areas between the Yellow River and the Huai River, Northern China, Northeastern China, Southwestern China and Northwestern China, and effective measures of biological prevention and control of mythimnaseparata walker have not yet been found.

Recently Plant Biotechnology Journal published online the research thesis by the team of Prof. Hada from the School of Life Sciences of IMU entitled Improvement of host-induced gene silencing efficiency via polycistronic-tRNA-amiR expression for multiple target genes and characterization of RNAi mechanism in Mythimna separata. Plant Biotechnology Journal is a TOP journal of Section 1 of Botany with IF=8.15.

The team of Prof. Hada has been committed to the studies of controlling mythimnaseparata walker through RNAi technology and has identified MsChi1and MsChi2, two ideal target genes in coding insect chitinasein their preceding endeavors. The research expounded on the studies of host-pest trans-kingdom RNAi and attempts to explore the intrinsic mechanism of this strategy. The research is significant in the following aspects. First, the tRNA-amiR (PTA) system employed in the research facilitates the simultaneous silencing of multiple target genes of the recipient insects through trans-kindgom modes. Second, the research reports the characteristics of the siRNA of lepidopterid insects and analyzes the differences and similarities when induced by different RNAi effectors, which will contribute to the promotion of RNAi-based control methods. Third, the in-depth bio-chemical analysis of the pathway constituent proteins of RNAi, in combination with the siRNA sequencing result, offers a deeper insight into the RNAi mechanism of lepidopterid insects. To sum up, the thesis conducts in-depth studies of the pathway, mechanism and efficiency of the RNAi of lepidopterid insects, and the PTA system will prompt the development of HIGS-based insect control strategies.

The thesis has Bao Wenhua, a doctoral student as the first author and Prof. Hada as the corresponding author. Prof. Li Xugang from the School of Life Sciences of Shandong Agricultural University participated in the project. The project was sponsored by the Innovation Guidance Program of Inner Mongolia Autonomous Region,the Science and Technology Planning Program of Inner Mongolia Autonomous Region, the National Natural Science Foundation of China, the Natural Science Foundation of Inner Mongolia Autonomous Region and the Open Project of the National Key Laboratory of Crop Biology of Shandong Agricultural University.

Url for the thesis: https://onlinelibrary.wiley.com/doi/10.1111/pbi.13555