Ethylene-Mediated Production and Emission of Limonene Influence Brown Planthopper Preference for Rice Plants

Volatile organic compounds (VOCs) play a key role in plant communication with other organisms in the natural environment. However, the regulatory role of the phytohormone ethylene in volatile production in plants remains unclear. In this study, we demonstrated that the application of an ethylene precursor and amplification of ethylene signaling make rice plants more attractive to brown planthopper (BPH) females for feeding and oviposition. A combination of transcriptome and VOCs analyses indicated that overexpression of OsEIL1, a master transcription factor in the ethylene pathway, influences the transcript levels of several terpene synthase genes as well as the production of volatile terpenes. Further investigation revealed that the expression of the limonene synthase gene, OsTPS19, was down-regulated in OsEIL1-overexpressing rice plants, leading to a decrease in limonene production and release. Genetic analysis confirmed the essential role of limonene in the OsEIL1-mediated attractiveness of rice plants to BPH. Our findings provide new perspectives for understanding the role of ethylene signaling in volatile-mediated plant-insect interactions.