Meuwly P., Molders W., Buchala A., Metraux J. P.
Institut de Biologie Vegetale, Rue Albert-Gockel 3, Universite de Fribourg, CH-1700 Fribourg, Switzerland.
Plant Physiol. 1995 Nov;109(3):1107-1114. doi: 10.1104/pp.109.3.1107.
Radiolabeling studies showed that salicylic acid (SA), an essential component in the signal transduction pathway leading to systemic acquired resistance, is synthesized from phenylalanine (Phe) and benzoic acid in cucumber (Cucumis sativus L.) plants inoculated with pathogens. Leaf discs from plants inoculated with either tobacco necrosis virus or Pseudomonas lachrymans incorporated more [14C]Phe into [14C]SA than mock-inoculated controls. The identity of SA was confirmed by gas chromatography-mass spectrometry. No reduction in specific activity of [14C]SA was observed for either free or bound SA between control and infected plants after feeding [14C]Phe. A specific inhibitor of Phe ammonia-lyase, 2-aminoindan-2-phosphonic acid, completely inhibited the incorporation of [14C]Phe into [14C]SA, although plants treated with 2-aminoindan-2-phosphonic acid could still produce [14C]SA from [14C]benzoic acid. Biosynthesis of SA in tissue inoculated with tobacco necrosis virus followed a transient pattern with the highest induction occurring 72 h postinoculation. Uninfected tissues from an infected plant synthesized de novo more SA than did controls. This suggests the involvement of a systemic signal triggering SA synthesis in tissue distant from the site of infection that display systemic acquired resistance.
放射性标记研究表明，水杨酸（SA）是导致系统获得性抗性的信号转导途径中的一种重要成分，在接种病原体的黄瓜（Cucumis sativus L.）植株中，它由苯丙氨酸（Phe）和苯甲酸合成。接种烟草坏死病毒或黄瓜角斑病菌的植株的叶圆片比模拟接种的对照植株将更多的[14C]苯丙氨酸掺入[14C]水杨酸中。通过气相色谱 - 质谱法确认了水杨酸的身份。在饲喂[14C]苯丙氨酸后，对照植株和受感染植株之间，游离态或结合态的[14C]水杨酸的比活性均未观察到降低。苯丙氨酸解氨酶的特异性抑制剂2 - 氨基茚 - 2 - 膦酸完全抑制了[14C]苯丙氨酸掺入[14C]水杨酸，尽管用2 - 氨基茚 - 2 - 膦酸处理的植株仍能从[14C]苯甲酸产生[14C]水杨酸。接种烟草坏死病毒的组织中水杨酸的生物合成呈现出一种短暂的模式，在接种后72小时诱导作用最强。来自受感染植株的未感染组织从头合成的水杨酸比对照更多。这表明存在一种系统信号，可触发远离感染部位的组织中水杨酸的合成，这些组织表现出系统获得性抗性。
