1.背景：
水杨酸（Salicylic acid，SA）是重要的植物激素，参与植物的生物胁迫和非生物胁迫响应。植物中有两条水杨酸合成途径：异分支酸合成酶途径（Isochorismate Synthase, ICS）和苯丙氨酸解氨酶途径（PhenylalanineAmmonia Lyase, PAL）。在拟南芥中，病原菌诱导的SA生物合成大约有10%是通过苯丙氨酸解氨酶途径实现，而90%的SA都是通过异分支酸合成酶途径合成。在异分支酸合成酶途径中，异分支酸合酶 ( isochorismate synthase 1, ICS1) 催化分支酸 (chorismic acid, CA ) 生成异分支酸 (isochorismate, ISC)。
2.结论：
Phytophthora sojae and Verticillium dahliaesecrete isochorismatases (PsIsc1 and VdIsc1).
PsIsc1 and VdIsc1 can suppress salicylate-mediated innate immunity in planta and
hydrolyse isochorismate in vitro.PsIsc1 and VdIsc1 lack signal peptides, but
exhibit characteristics that lead to unconventional secretion.PsIsc1 and VdIsc1
disrupt the plant salicylate metabolism pathway by hydrolysing its precursor isochorismate.
3.日积月累
Triad: [ˈtraɪæd]
n. 三和音；三个一组；三价元素；三合会（华人黑社会）；三合会成员；三人组合；三件套；三和弦；三题词
Thread: [θred]
n. 线；螺纹；思路；衣服；线状物；玻璃纤维；路线
vt. 穿过；穿线于；使交织
vi. 通过；穿透过
Hyphae:[ˈhaɪˌfiː]
n. 菌丝（hypha的复数形式）
Transformant: [trænz'fɔmənt]
n. 转化株（指已经转化的细菌细胞）
Salicylate (SA) is a central signalingmolecule during plant innate immune responses. It is usually induced byinfection with biotrophic or hemibiotrophic pathogens, and serves as an importantcomponent of PAMP-triggered immunity (PTI), effector-triggered immunity andsystemic acquired resistance. Plants synthesize SA through two distinctenzymatic pathways. One is from phenylalanine via cinnamate and the other isfrom chorismate via isochorismate. Pseudomonas aeruginosa produces SA via twodistinct enzymes: isochorismate synthase (ICS) and isochorismate pyruvate lyase11. ICS homologues have beenidentified in a wide variety of plant species and genetic analyses revealedthat the ICS-dependent SA biosynthetic pathway predominates under (a)bioticstresses in Arabidopsis, although IPL genes have not yet been identified inplants. Isochorismate is a precursor of both SA andmany other distinct derivatives in plants, fungi and bacteria.
NahG gene encodes salicylate hydroxylase,an enzyme that converts SA to catechol(邻苯二酚，[有化] 儿茶酚).
网友评论