A Salivary Endo-β-1,4-Glucanase Acts as an Effector That Enables the Brown Planthopper to Feed on Rice.

The brown planthopper (BPH) Nilaparvata lugens is one of the most destructive insect pests on rice (Oryza sativa) in Asia. After landing on plants, BPH rapidly accesses plant phloem and sucks the phloem sap through unknown mechanisms. We discovered a salivary endo-β-1,4-glucanase (NlEG1) that has endoglucanase activity with a maximal activity at pH 6 at 37°C and is secreted into rice plants by BPH NlEG1 is highly expressed in the salivary glands and midgut. Silencing NlEG1 decreases the capacity of BPH to reach the phloem and reduces its food intake, mass, survival, and fecundity on rice plants. By contrast, NlEG1 silencing had only a small effect on the survival rate of BPH raised on artificial diet. Moreover, NlEG1 secreted by BPH did not elicit the production of the defense-related signal molecules salicylic acid, jasmonic acid, and jasmonoyl-isoleucine in rice, although wounding plus the application of the recombination protein NlEG1 did slightly enhance the levels of jasmonic acid and jasmonoyl-isoleucine in plants compared with the corresponding controls. These data suggest that NlEG1 enables the BPH's stylet to reach the phloem by degrading celluloses in plant cell walls, thereby functioning as an effector that overcomes the plant cell wall defense in rice.

Ji R ，Ye W ，Chen H ，Zeng J ，Li H ，Yu H ，Li J ，Lou Y ... -  《-》

A salivary EF-hand calcium-binding protein of the brown planthopper Nilaparvata lugens functions as an effector for defense responses in rice.

Ye W ，Yu H ，Jian Y ，Zeng J ，Ji R ，Chen H ，Lou Y ... -  《Scientific Reports》

A Salivary Odorant-Binding Protein Mediates Nilaparvata lugens Feeding and Host Plant Phytohormone Suppression.

Liu H ，Wang C ，Qiu CL ，Shi JH ，Sun Z ，Hu XJ ，Liu L ，Wang MQ ... -  《-》

Transcriptomics identifies key defense mechanisms in rice resistant to both leaf-feeding and phloem feeding herbivores.

Li Y ，Cheah BH ，Fang YF ，Kuang YH ，Lin SC ，Liao CT ，Huang SH ，Lin YF ，Chuang WP ... -  《BMC PLANT BIOLOGY》

Planthopper-Secreted Salivary Calmodulin Acts as an Effector for Defense Responses in Rice.

The brown planthopper (Nilaparvata lugens, BPH) and small brown planthopper (Laodelphax striatellus, SBPH) are major pests of rice (Oryza sativa) in Asia. These piercing-sucking insects secrete saliva into the host during feeding. Nevertheless, it is largely unknown how planthoppers use salivary effectors to enable continuous feeding on rice. Here, we screened their salivary proteomes and selected eight salivary proteins conserved between SBPH and BPH as candidate effectors. Silencing calmodulin (CaM) impeded BPH and SBPH from penetrating the phloem. Hence, their food intake, survival, and fecundity on rice plants were reduced. By contrast, CaM silencing had a small effect on the survival rate of BPH and SBPH raised on artificial diet. The CaM amino acid sequences were the same for both BPH and SBPH. CaM was highly expressed in their salivary glands and secreted into the rice plants during feeding. Bacterially expressed recombinant CaM protein exhibited calcium-binding activity. In planta expression disclosed that CaM was localized to the plant cytoplasms and nuclei and suppressed plant defenses such as hydrogen peroxide (H2O2) accumulation and callose deposition. CaM-silenced BPH and SBPH nymphs elicited relatively high levels of H2O2 and callose accumulation in rice plants. The foregoing results reveal that CaM is an effector as it enables the planthopper to reach the phloem by suppressing callose deposition and H2O2 accumulation in rice.

Fu J ，Shi Y ，Wang L ，Tian T ，Li J ，Gong L ，Zheng Z ，Jing M ，Fang J ，Ji R ... -  《-》