巴西橡胶树4－羟基－3－甲基－2-(E)－丁烯基－4－磷酸还原酶基因(Hb-HDR)的克隆及表达分析

Cloning and Expression of HbHDR from Hevea brasiliensis

4-羟基-3-甲基-2-(E)-丁烯基-4-磷酸还原酶(4-hydroxy-3-methyl-2-(E)-butenyl-4-diphosphate reductase,HDR)是异戊烯基焦磷酸合成途径之一甲基赤藓糖磷酸(methylerythritol phosphate,MEP)途径中的最后一个酶,催化4-羟基-3-甲基-(2E)-丁烯基-4-磷酸生成异戊烯基焦磷酸。根据植物HDR的同源序列设计引物,通过RT-PCR结合RACE的方法在橡胶树中获得了与其相应的HDR基因,命名为HbHDR。序列分析表明HbHDR长1627bp,编码462个氨基酸,属于LYTB家族,该氨基酸序列与烟草、长春花、胡黄连、拟南芥、银杏和火炬松的HDR同源性为79.1%、78.4%、76.5%、75.3%、72.2%和70.9%。半定量RT-PCR结果显示,乙烯诱导胶乳HbHDR的表达。

4-hydroxy-3-methyl-2-（E）-butenyl-4-diphosphate reductase （HDR） is proved to be the terminal-acting enzyme in the plastid MEP pathway which provides isoprenoids. The full-length cDNA encoding a HDR, designated as HbHDR, was isolated for the first time from Hevea brasiliensis by the RACE method. HbHDR contained a 1 627-hp open reading frame encoding 462 amino acids. The deduced HbHDR, which shared 79.1%, 78.4%, 76.5%, 75.3%, 72.2% and 70.9% identities with the HDR protein from Nicotiana langsdorffiixNicotiana sandera, Catharan- thus roseus, Picrorhiza kurrooa, A rabidopsis thaliana, Ginkgo biloba and Pinus taeda, belonged to the LYTB family. Transcription pattern analysis revealed that HbHDR was constitutively expressed in laticifer, barks and leaf. The transcription of HbHDR in latex was induced by ethephon.