1.背景：
水楊酸（Salicylic acid，SA）是重要的植物激素，參與植物的生物脅迫和非生物脅迫響應(yīng)。植物中有兩條水楊酸合成途徑：異分支酸合成酶途徑（Isochorismate Synthase, ICS）和苯丙氨酸解氨酶途徑（PhenylalanineAmmonia?Lyase, PAL）。在擬南芥中，病原菌誘導(dǎo)的SA生物合成大約有10%是通過(guò)苯丙氨酸解氨酶途徑實(shí)現(xiàn)，而90%的SA都是通過(guò)異分支酸合成酶途徑合成。在異分支酸合成酶途徑中，異分支酸合酶 ( isochorismate synthase 1, ICS1) 催化分支酸 (chorismic?acid, CA ) 生成異分支酸 (isochorismate, ISC)。
2.結(jié)論：
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.日積月累
Triad: [?tra??d]
n. 三和音；三個(gè)一組；三價(jià)元素；三合會(huì)（華人黑社會(huì)）；三合會(huì)成員；三人組合；三件套；三和弦；三題詞
Thread: [θred]
n. 線；螺紋；思路；衣服；線狀物；玻璃纖維；路線
vt. 穿過(guò)；穿線于；使交織
vi. 通過(guò)；穿透過(guò)
Hyphae:[?ha??fi?]
n. 菌絲（hypha的復(fù)數(shù)形式）
Transformant: [tr?nz'f?m?nt]
n. 轉(zhuǎn)化株（指已經(jīng)轉(zhuǎn)化的細(xì)菌細(xì)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(鄰苯二酚，[有化] 兒茶酚).
