Chunling Xu1,2, Chengye Lu1, Jun Piao2, Yixiao Wang2, Tong Zhou1, Yijun Zhou1, Shuo Li1,3,4. 1. Institute of Plant Protection, Jiangsu Key Laboratory for Food Quality and Safety - State Key Laboratory Cultivation Base, Ministry of Science and Technology, Jiangsu Academy of Agricultural Sciences, Nanjing, China. 2. School of Life Science, Liaoning Normal University, Dalian, China. 3. State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, China. 4. School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China.
Abstract
BACKGROUND: The transmission of plant viruses by arthropod vectors is closely related to feeding behavior. For persistently transmitted viruses, virus release means that virus moves through the salivary gland microvillus barriers of insects into plant via the stylet. However, whether virus release is dependent on plant tissue and component recognition by the stylet is unclear. RESULTS: In this study, the small brown planthopper (SBPH) and two rice viruses transmitted by it were used as a model to explore this question. After the viruliferous insects penetrated a stretched membrane without plant tissue structure and ingested liquid food (rice sap, nutrient solution or water), both viruses were detected in the liquid food after only a 6 min inoculation access period, suggesting that the viruses were released from SBPH salivary gland independent of plant tissue and component recognition by the stylet. In subsequent electrical penetration graph (EPG) analysis, N4a-like and N4b-like waveforms, similar to N4a (phloem salivation before ingestion) and N4b (sieve element ingestion), were observed during SBPH penetrating the membrane, exhibiting normal feeding activity of planthopper on membrane, which further demonstrated that virus release from salivary gland was along with feeding activity, without the stylet sensing plant tissue. EPG analysis and identification of salivary proteins indicated more active feeding behavior and efficient salivation in viruliferous planthoppers. CONCLUSION: These results suggest that the rice virus is released from insect salivary gland independent of plant tissue and component recognition by the stylet, and the simple virus release mode facilitates virus transmission by vectors.
BACKGROUND: The transmission of plant viruses by arthropod vectors is closely related to feeding behavior. For persistently transmitted viruses, virus release means that virus moves through the salivary gland microvillus barriers of insects into plant via the stylet. However, whether virus release is dependent on plant tissue and component recognition by the stylet is unclear. RESULTS: In this study, the small brown planthopper (SBPH) and two rice viruses transmitted by it were used as a model to explore this question. After the viruliferous insects penetrated a stretched membrane without plant tissue structure and ingested liquid food (rice sap, nutrient solution or water), both viruses were detected in the liquid food after only a 6 min inoculation access period, suggesting that the viruses were released from SBPH salivary gland independent of plant tissue and component recognition by the stylet. In subsequent electrical penetration graph (EPG) analysis, N4a-like and N4b-like waveforms, similar to N4a (phloem salivation before ingestion) and N4b (sieve element ingestion), were observed during SBPH penetrating the membrane, exhibiting normal feeding activity of planthopper on membrane, which further demonstrated that virus release from salivary gland was along with feeding activity, without the stylet sensing plant tissue. EPG analysis and identification of salivary proteins indicated more active feeding behavior and efficient salivation in viruliferous planthoppers. CONCLUSION: These results suggest that the rice virus is released from insect salivary gland independent of plant tissue and component recognition by the stylet, and the simple virus release mode facilitates virus transmission by vectors.