Catinot Jérémy, Buchala Antony, Abou-Mansour Eliane, Métraux Jean-Pierre
Department of Biology, University of Fribourg, Ch. du Musée 10, 1700 Fribourg, Switzerland.
FEBS Lett. 2008 Feb 20;582(4):473-8. doi: 10.1016/j.febslet.2007.12.039. Epub 2008 Jan 15.
Salicylic acid (SA) is an important signal involved in the activation of defence responses against abiotic and biotic stress. In tobacco, benzoic acid or glucosyl benzoate were proposed to be precursors of SA. This is in sharp contrast with studies in Arabidopsis thaliana, where SA derives from isochorismate. We have determined the importance of isochorismate for SA biosynthesis in Nicotiana benthamiana using virus-induced gene silencing of the isochorismate synthase (ICS) gene. Plants with silenced ICS expression do not accumulate SA after exposure to UV or to pathogen stress. Plants with silenced ICS expression also exhibit strongly decreased levels of phylloquinone, a product of isochorismate. Our data provide evidence for an isochorismate-derived synthesis of SA in N. benthamiana.
水杨酸（SA）是参与激活针对非生物和生物胁迫的防御反应的重要信号。在烟草中，苯甲酸或苯甲酸葡萄糖酯被认为是SA的前体。这与拟南芥中的研究形成鲜明对比，在拟南芥中SA来源于异分支酸。我们利用病毒诱导的异分支酸合酶（ICS）基因沉默技术，确定了异分支酸在本氏烟草SA生物合成中的重要性。ICS表达沉默的植株在暴露于紫外线或病原体胁迫后不会积累SA。ICS表达沉默的植株还表现出叶绿醌水平大幅下降，叶绿醌是异分支酸的产物。我们的数据为异分支酸在本氏烟草中合成SA提供了证据。
