烟粉虱MED隐种拒避7-表姜烯的嗅觉分子机制

Cultivated tomato can suffer devastating loss from tobacco whitefly Bemisia tabaci (Gennadius) by their directly sucking and transmitting TYLCV, while wild tomato Solanum habrochaites is far less attractive to this insect. It is reported that B.tabaci show innate avoidance to 7-epizingiberene, which is a major component released from S.habrochaites. However，the mechanism of avoidance behavior to this chiral compound in Bemisia tabaci is not clear. In this project, B.tabaci MED is chosen as research target, and the target odorant-binding proteins (OBPs) specifically binding 7-epizingiberene will be identified by fluorescence competitive binding assays. According to the binding affinity in ligand-binding assays of the mutants which is generated by in silico protein structure modeling and site-directed mutagenesis technique, the key active residues of the target OBPs will be identified. The role of the target OBP genes will be further validated by RNA interference. The effect of RNA interference will be confirmed by behavioral assays of repellent activities and biological characteristics. The results will clarify the olfactory molecular mechanisms of innate avoidance behavior to 7-epizingiberene in B.tabaci MED, and provide theory base for the B.tabaci behavioral manipulation.

烟粉虱Bemisia tabaci (Gennadius)通过直接刺吸和传播番茄黄化曲叶病毒，能对栽培番茄产量造成毁灭性的损失。然而烟粉虱对野生多毛番茄却极少危害。研究表明，该虫对野生多毛番茄的主要挥发组分7-表姜烯(7-epizingiberene)具有先天的拒避性。但烟粉虱拒避该手性化合物的内在机制尚不清楚。鉴于此，本项目以烟粉虱MED隐种为研究对象，通过蛋白表达纯化、荧光竞争结合实验，明确特异识别7-表姜烯的气味结合蛋白(OBPs)。进一步通过同源建模、定点突变和功能研究，揭示靶标OBPs特异结合7-表姜烯的关键结构区域。并利用RNA干扰技术，研究靶标OBPs基因被抑制前后，该虫对7-表姜烯拒避行为和生物学特征的变化。研究结果将揭示烟粉虱MED隐种拒避7-表姜烯的嗅觉分子机制，为制定科学的行为调控策略提供理论依据。

烟粉虱Bemisia tabaci (Gennadius)通过直接刺吸和传播病毒，能对栽培番茄造成严重损失。然而在野外自然环境下，烟粉虱对野生多毛番茄却极少危害，但烟粉虱识别多毛番茄化合物的分子机理尚未解析。本项目研究证实了7-表姜烯及其稳定形式R-芳姜黄烯是野生多毛番茄的主要挥发组分。进一步结合生物信息学和qRT-PCR分析，鉴定到了识别R-芳姜黄烯的关键气味结合蛋白(OBPs)。 通过蛋白表达纯化、荧光竞争结合实验，明确了OBP1为特异识别R-芳姜黄烯的OBP。进一步通过同源建模、定点突变和功能研究，发现OBP1第108位的天冬酰胺是影响OBP1和R-芳姜黄烯结合的关键氨基酸残基。并利用RNA干扰技术，确认了OBP1在烟粉虱体内识别多毛番茄挥发物的功能。研究结果揭示了烟粉虱MED隐种拒避野生多毛番茄挥发物的嗅觉分子机制，为烟粉虱的行为调控策略提供了理论依据。