An salivary effector SfPDI regulates plant defense to improve the foraging of Spodoptera frugiperda

Studies on the interaction between herbivorous insects and plants mediated by insect secretions have been paid more and more attention in chewing mouthparts insects, but the molecular mechanism has been rarely reported. We identified a SfPDI protein from the salivary glands of S. frugiperda that regulates the interaction between S. frugiperda and plants. Here, we found that the salivary protein SfPDI is mainly highly expressed in the salivary glands of Spodoptera frugiperda and can be secreted into plants as a secreted protein. SfPDI will be responded by S. frugiperda feeding on host plants, and the response effect is stronger at 2h. Transient expression of SfPDI will lead to necrosis of tobacco leaves and accumulation of ROS. Gene silencing experiments showed that SfPDI contributed to the growth and development of S. frugiperda, and the S. frugiperda larvae preferred to feed on tobacco leaves transiently expressing SfPDI. This work supports further exploration of insect-plant interaction mechanisms and provides a theoretical basis for developing insect-resistant germplasm and green pest control strategies.