Salivary DN ase II from Laodelphax striatellus acts as an effector that suppresses plant defence

Summary Extracellular DNA , released by damaged plant cells, acts as a damage‐associated molecular pattern ( DAMP ). We demonstrated previously that the small brown planthopper ( Laodelphax striatellus , SBPH ) secreted DN ase II when feeding on artificial diets. However, the function of DN ase II in insect feeding remained elusive. The influences of DN ase II on SBPH s and rice plants were investigated by suppressing expression of DN ase II or by application of heterogeneously expressed DN ase II . We demonstrated that DN ase II is mainly expressed in the salivary gland and is responsible for DNA ‐degrading activity of saliva. Knocking down the expression of DN ase II resulted in decreased performance of SBPH reared on rice plants. The ds DN ase II ‐treated SBPH did not influenced jasmonic acid (JA), salicylic acid (SA), ethylene (ET) pathways, but elicited a higher level of H 2 O 2 and callose accumulation. Application of heterogeneously expressed DN ase II in DN ase II ‐deficient saliva slightly reduced the wound‐induced defence response. We propose a DN ase II ‐based invading model for SBPH feeding on host plants, and provide a potential target for pest management.