State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
Plant Physiol. 2011 Jun;156(2):856-72. doi: 10.1104/pp.111.174334. Epub 2011 Apr 12.
We examined ways in which the Brown planthopper induced008a (Bphi008a; AY256682) gene of rice (Oryza sativa) enhances the plant's resistance to a specialist herbivore, the brown planthopper (BPH; Nilaparvata lugens). Measurement of the expression levels of ethylene synthases and of ethylene emissions showed that BPH feeding rapidly initiated the ethylene signaling pathway and up-regulated Bphi008a transcript levels after 6 to 96 h of feeding. In contrast, blocking ethylene transduction (using 1-methylcyclopropene) reduced Bphi008a transcript levels in wild-type plants fed upon by BPH. In vitro kinase assays showed that Bphi008a can be phosphorylated by rice Mitogen-activated Protein Kinase5 (OsMPK5), and yeast two-hybrid assays demonstrated that the carboxyl-terminal proline-rich region of Bphi008a interacts directly with this kinase. Furthermore, bimolecular fluorescence complementation assays showed that this interaction occurs in the nucleus. Subsequently, we found that Bphi008a up-regulation and down-regulation were accompanied by different changes in transcription levels of OsMPK5, OsMPK12, OsMPK13, and OsMPK17 in transgenic plants. Immunoblot analysis also showed that the OsMPK5 protein level increased in overexpressing plants and decreased in RNA interference plants after BPH feeding. In transgenic lines, changes in the expression levels of several enzymes that are important components of the defenses against the BPH were also observed. Finally, yeast two-hybrid screening results showed that Bphi008a is able to interact with a b-ZIP transcription factor (OsbZIP60) and a RNA polymerase polypeptide (SDRP).
我们研究了水稻(Oryza sativa)中 Brown planthopper 诱导 008a(Bphi008a;AY256682)基因增强植物对专食性昆虫褐飞虱(BPH;Nilaparvata lugens)抗性的方式。对乙烯合成酶和乙烯排放的测量表明,BPH 取食迅速启动了乙烯信号通路,并在取食后 6 至 96 小时上调了 Bphi008a 转录本水平。相比之下,使用 1-甲基环丙烯阻断乙烯转导会降低 BPH 取食的野生型植株中 Bphi008a 的转录本水平。体外激酶测定表明,Bphi008a 可被水稻丝裂原活化蛋白激酶 5(OsMPK5)磷酸化,酵母双杂交试验表明 Bphi008a 的羧基端富含脯氨酸区直接与该激酶相互作用。此外,双分子荧光互补测定表明这种相互作用发生在细胞核中。随后,我们发现 Bphi008a 的上调和下调伴随着转植物中 OsMPK5、OsMPK12、OsMPK13 和 OsMPK17 的转录水平发生不同变化。免疫印迹分析还表明,在 BPH 取食后,过表达植物中 OsMPK5 蛋白水平增加,RNAi 植物中 OsMPK5 蛋白水平降低。在转基因株系中,还观察到几种对 BPH 防御很重要的酶的表达水平发生变化。最后,酵母双杂交筛选结果表明 Bphi008a 能够与 b-ZIP 转录因子(OsbZIP60)和 RNA 聚合酶多肽(SDRP)相互作用。