State Key Laboratory of Biocontrol, Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
Plant Cell Rep. 2013 Jul;32(7):1075-84. doi: 10.1007/s00299-013-1389-2. Epub 2013 Jan 24.
Silencing OsMPK3 decreased elicited JA levels, which subsequently reduced levels of herbivore-induced trypsin protease inhibitors (TrypPIs) and improved the performance of SSB larvae, but did not influence BPH. Mitogen-activated protein kinases (MPKs) are known to play an important role in plant defense by transferring biotic and abiotic signals into programmed cellular responses. However, their functions in the herbivore-induced defense response in rice remain largely unknown. Here, we identified a MPK3 gene from rice, OsMPK3, and found that its expression levels were up-regulated in response to infestation by the larvae of the striped stem borer (SSB) (Chilo suppressalis), to mechanical wounding and to treatment with jasmonic acid (JA), but not to infestation by the brown planthopper (BPH) Nilaparvata lugens or to treatment with salicylic acid. Moreover, mechanical wounding and SSB infestation induced the expression of OsMPK3 strongly and quickly, whereas JA treatment induced the gene more weakly and slowly. Silencing OsMPK3 (ir-mpk3) reduced the expression of the gene by 50-70 %, decreased elicited levels of JA and diminished the expression of a lipoxygenase gene OsHI-LOX and an allene oxide synthase gene OsAOS1. The reduced JA signaling in ir-mpk3 plants decreased the levels of herbivore-induced trypsin protease inhibitors (TrypPIs) and improved the performance of SSB larvae, but did not influence BPH. Our findings suggest that the gene OsMPK3 responds early in herbivore-induced defense and can be regulated by rice plants to activate a specific and appropriate defense response to different herbivores.
沉默 OsMPK3 降低了诱导的 JA 水平，从而降低了草食性诱导的胰蛋白酶抑制剂（TrypPIs）的水平，并提高了 SSB 幼虫的性能，但对 BPH 没有影响。丝裂原活化蛋白激酶（MPKs）通过将生物和非生物信号传递到程序化的细胞反应中，在植物防御中起着重要作用。然而，它们在水稻中对草食性诱导防御反应的功能在很大程度上尚不清楚。在这里，我们从水稻中鉴定出一个 MPK3 基因 OsMPK3，并发现其表达水平在受到斜纹夜蛾（SSB）（Chilo suppressalis）幼虫侵袭、机械损伤和茉莉酸（JA）处理时上调，但在受到褐飞虱（BPH）Nilaparvata lugens 侵袭或水杨酸处理时没有上调。此外，机械损伤和 SSB 侵染强烈且快速地诱导 OsMPK3 的表达，而 JA 处理则较弱且较慢地诱导该基因的表达。沉默 OsMPK3（ir-mpk3）使该基因的表达降低了 50-70%，降低了诱导的 JA 水平，并减弱了脂氧合酶基因 OsHI-LOX 和丙二烯氧化物合酶基因 OsAOS1 的表达。ir-mpk3 植物中降低的 JA 信号降低了草食性诱导的胰蛋白酶抑制剂（TrypPIs）的水平，并改善了 SSB 幼虫的性能，但对 BPH 没有影响。我们的研究结果表明，基因 OsMPK3 对草食性诱导的防御反应较早作出响应，并可被水稻植株调控以激活针对不同草食性的特定而适当的防御反应。
