Rice (Oryza sativa L.), which is a staple food for more than half of the world’s population, is frequently attacked by herbivorous insects, including the rice stem borer, Chilo suppressalis. C. suppressalis substantially reduces rice yields in temperate regions of Asia, but little is known about how rice plants defend themselves against this herbivore at molecular and biochemical level. In the current study, we combined next-generation RNA sequencing and metabolomics techniques to investigate the changes in gene expression and in metabolic processes in rice plants that had been continuously fed by C. suppressalis larvae for different durations (0, 24, 48, 72, and 96 h). Furthermore, the data were validated using quantitative real-time PCR. There were 4,729 genes and 151 metabolites differently regulated when rice plants were damaged by C. suppressalis larvae. Further analyses showed that defense-related phytohormones, transcript factors, shikimate-mediated and terpenoid-related secondary metabolism were activated, whereas the growth-related counterparts were suppressed by C. suppressalis feeding. The activated defense was fueled by catabolism of energy storage compounds such as monosaccharides, which meanwhile resulted in the increased levels of metabolites that were involved in rice plant defense response. Comparable analyses showed a correspondence between transcript patterns and metabolite profiles. The current findings greatly enhance our understanding of the mechanisms of induced defense response in rice plants against C. suppressalis infestation at molecular and biochemical levels, and will provide clues for development of insect-resistant rice varieties.

A newly developed breeding variety of crops shows high resistance in laboratory conditions but exhibits low resistance to target insects in the field. This research aims to explain this phenomenon from inter-species interactions in insects as the herbivory by one insect species can induce physiological changes in plants that enhance attraction other insect species. The striped stem borer (SSB),Chilo suppressalis(Walker), and the brown planthopper (BPH),Nilaparvata lugens(Stål), are pests of rice (Oryza sativaL.) that cause major losses in grain production. This study examines how BPH feeding behavior on rice is affected by SSB herbivory. BPH performance and behavior were tested on the planthopper-resistant rice variety ‘Mudgo’ with pre-feeding of SSB. BPHs showed better growth and development, as well as feeding behavior, on SSB-damaged plants when compared to healthy/undamaged plants. Analysis of gene expression and phytohormone level revealed changes in the jasmonic acid (JA) biosynthesis in response to SSB feeding. The analysis of central metabolites and volatiles showed that SSB-damaged stem induced the volatiles emission, which benefits planthopper development or attracts BPH. In summary, we found that the JA biosynthesis was triggered by SSB and played a vital role in rice defense against BPH. This provides insight into the molecular and biochemical mechanisms of BPH preferences for SSB-damaged rice plants. Our study emphasizes the crucial role of inter-species interactions in enhancing host plant resistance to insect pests and evaluating germplasm resistance. These findings can serve as a basis for controlling BPH.