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

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Abstract 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, Nl Annexin-like5 ( Nl ANX5), 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. Nl ANX5 targets rice annexin ( Os ANN) proteins, including Os ANN2 and Os ANN8. Further analysis with Nl ANX5 and Os ANN2 as well as Os ANN8 showed that Nl ANX5 displaces Os ANN2 and Os ANN8 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. Significance Statement Insect pests pose a serious biotic threat to crop production worldwide. Understanding how insect pests attack plants could inspire innovative pest control measures to enhance global food security. The brown planthopper (BPH; Nilaparvata lugens Stål) is the most devastative insect pest in rice. In this study, we discovered that BPH secretes a salivary protein, Nl Annexin-like5 ( Nl ANX5), to target rice host annexins that are associated with calcium fluxes and activation of multiple rice defense pathways. This knowledge led to employing enhanced expression of rice annexin-encoding genes to successfully defeat the virulence function of Nl ANX5. Results have significant implications in the development of anti-virulence breeding strategies against BPH.

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