Augment rice ANNEXIN expression to counter planthopper NlAnnexin-like5 as an anti-virulence strategy against a major crop pest

The brown planthopper (BPH) is the most devastating insect pest in rice, posing a serious threat to global rice production. One attractive control strategy would be based on the understanding of the virulence mechanisms of BPH at the molecular level and then designing targeted methods to neutralize such mechanisms. Salivary proteins of BPH are important players in mediating rice-BPH interactions. Here, we describe a pivotal role of a watery saliva protein, NlAnnexin-like5 (NlANX5), in the rice-BPH interaction. RNA interference (RNAi) of NlANX5 greatly compromised BPH feeding performance and survival rate on rice plants. NlANX5-RNAi BPH triggered a rapid calcium ion influx in rice cells. The feeding and survival defects of NlANX5-RNAi BPH can be restored in NlANX5-expressing transgenic rice plants. NlANX5 targets rice annexin (OsANN) proteins, including OsANN2 and OsANN8. Further analysis with NlANX5 and OsANN2 as well as OsANN8 showed that NlANX5 displaces OsANN2 and OsANN8 from the rice cell membrane. The osann2 osann8 mutant rice plants are hypersusceptible to BPH infestation. In contrast, enhanced expression of OsANN2 and OsANN8 gene resulted in robust rice resistance against BPH. This study highlights a successful example of identifying and augmenting the expression of the host targets of a major BPH virulence effector as a promising anti-virulence strategy against an important crop pest.