Department of Molecular Biotechnology, Ghent University, Coupure links 653, B-9000, Ghent, Belgium.
New Phytol. 2012 Nov;196(3):901-913. doi: 10.1111/j.1469-8137.2012.04310.x. Epub 2012 Sep 17.
Studies involving plant-nematode interactions provide an opportunity to unravel plant defense signaling in root tissues. In this study, we have characterized the roles of salicylate (SA), jasmonate (JA), ethylene (ET) and abscisic acid (ABA) in plant defense against the migratory nematode Hirschmanniella oryzae in the monocot model plant rice (Oryza sativa). Experiments with exogenous hormone applications, biosynthesis inhibition and mutant/transgenic lines were executed to test the effect on H. oryzae parasitism in rice roots. Our results demonstrate that an intact ET, JA and SA biosynthesis pathway is a prerequisite for defense against H. oryzae. By contrast, exogenous ABA treatment drastically compromised the rice defense towards this nematode. Gene expression analyses using quantitative reverse transcription polymerase chain reaction (qRT-PCR) demonstrate that the disease-inducing effect of ABA is likely to be the result of an antagonistic interaction between this hormone and the SA/JA/ET-dependent basal defense system. Collectively, in rice defense against H. oryzae, at least three pathways, namely SA, JA and ET, are important, while ABA plays a negative role in defense. Our results suggest that the balance of ABA and SA/JA/ET signaling is an important determinant for the outcome of the rice-H. oryzae interaction.
植物-线虫相互作用的研究为揭示根系植物防御信号提供了机会。在这项研究中，我们研究了水杨酸（SA）、茉莉酸（JA）、乙烯（ET）和脱落酸（ABA）在单子叶模式植物水稻（Oryza sativa）抵抗迁徙线虫 Hirschmanniella oryzae 中的作用。通过外源激素处理、生物合成抑制和突变体/转基因系实验，测试了它们对水稻根中 H. oryzae 寄生的影响。我们的结果表明，完整的 ET、JA 和 SA 生物合成途径是防御 H. oryzae 的前提。相比之下，外源 ABA 处理严重损害了水稻对这种线虫的防御。使用定量逆转录聚合酶链反应（qRT-PCR）的基因表达分析表明，ABA 的致病作用可能是这种激素与 SA/JA/ET 依赖性基础防御系统之间拮抗相互作用的结果。总的来说，在水稻抵抗 H. oryzae 的过程中，至少有三条途径，即 SA、JA 和 ET 是重要的，而 ABA 在防御中起负面作用。我们的研究结果表明，ABA 和 SA/JA/ET 信号的平衡是决定水稻-H. oryzae 相互作用结果的重要决定因素。
