Huang Xi, Stettmaier Kurt, Michel Christa, Hutzler Peter, Mueller Martin J, Durner Jörg
Institute of Biochemical Plant Pathology, GSF--National Research Center for Environment and Health, 85764 Oberschleissheim, Germany.
Planta. 2004 Apr;218(6):938-46. doi: 10.1007/s00425-003-1178-1. Epub 2004 Jan 10.
Nitric oxide (NO) has been associated with plant defense responses during microbial attack, and with induction and/or regulation of programmed cell death. Here, we addressed whether NO participates in wound responses in Arabidopsis thaliana (L.) Heynh. Real-time imaging by confocal laser-scanning microscopy in conjunction with the NO-selective fluorescence indicator 4,5-diaminofluorescein diacetate (DAF-2 DA) uncovered a strong NO burst after wounding or after treatment with JA. The NO burst was triggered within minutes, reminiscent of the oxidative burst during hypersensitive responses. Furthermore, we were able to detect NO in plants (here induced by wounding) by means of electron paramagnetic resonance measurements using diethyldithiocarbamate as a spin trap. When plants were treated with NO, Northern analyses revealed that NO strongly induces key enzymes of jasmonic acid (JA) biosynthesis such as allene oxide synthase (AOS) and lipoxygenase (LOX2). On the other hand, wound-induced AOS gene expression was independent of NO. Furthermore, JA-responsive genes such as defensin (PDF1.2) were not induced, and NO induction of JA-biosynthesis enzymes did not result in elevated levels of JA. However, treatment with NO resulted in accumulation of salicylic acid (SA). In transgenic NahG plants (impaired in SA accumulation and/or signaling), NO did induce JA production and expression of JA-responsive genes. Altogether, the presented data demonstrate that wounding in Arabidopsis induces a fast accumulation of NO, and that NO may be involved in JA-associated defense responses and adjustments.
一氧化氮（NO）与植物在遭受微生物攻击时的防御反应以及程序性细胞死亡的诱导和/或调节有关。在此，我们探讨了NO是否参与拟南芥（L.）Heynh.的伤口反应。利用共聚焦激光扫描显微镜结合NO选择性荧光指示剂4,5-二氨基荧光素二乙酸酯（DAF-2 DA）进行实时成像，发现受伤后或用茉莉酸（JA）处理后会出现强烈的NO爆发。NO爆发在几分钟内触发，这让人联想到过敏反应中的氧化爆发。此外，我们能够通过使用二乙基二硫代氨基甲酸盐作为自旋捕获剂的电子顺磁共振测量来检测植物中的NO（此处由伤口诱导）。当用NO处理植物时，Northern分析表明NO强烈诱导茉莉酸（JA）生物合成的关键酶，如丙二烯氧化物合酶（AOS）和脂氧合酶（LOX2）。另一方面，伤口诱导的AOS基因表达与NO无关。此外，JA反应基因如防御素（PDF1.2）未被诱导，并且NO对JA生物合成酶的诱导并未导致JA水平升高。然而，用NO处理导致水杨酸（SA）积累。在转基因NahG植物（SA积累和/或信号传导受损）中，NO确实诱导了JA的产生和JA反应基因的表达。总之，所呈现的数据表明拟南芥中的伤口诱导了NO的快速积累，并且NO可能参与与JA相关的防御反应和调节。
