拟南芥尿黑酸叶绿醇转移酶(HPT)基因启动子的分离及表达特性分析

Isolation and Characterization of Homogentisate Phytyltransferase (HPT) Gene Promoter from Arabidopsis thaliana

尿黑酸叶绿醇转移酶(HPT)是催化生育酚生物合成分支途径中的关键酶,催化叶绿醇焦磷酸(phytyl-PP)与尿黑酸(HGA)缩合生成生育酚的前体。本研究从拟南芥中分离HPT基因的启动子序列946bp,构建了该启动子与GUS嵌合的重组载体,通过农杆菌介导转化拟南芥,取正常生长条件下的拟南芥转基因植株进行GUS组织化学染色,结果表明,在HPT启动子的驱动下,GUS基因主要在转基因拟南芥的根中高表达,在成熟叶片、花丝、雌蕊中也有一些表达,而在茎、根尖、花药、种荚及发育的种子中则未表达,可见该启动子为根优势表达启动子。

Homogentisate Phytyltransferase （HPT） is a key enzyme catalyzing condensation of HGA and PDP in the first step of tocopherol biosynthesis. The HPT gene has been cloned from several photosynthetic organisms. Overexpression of HPT in transgenic plants increases tocopherols significantly in leaves and seeds. A mutation of the Arabidopsis HPT gene results in tocopherol deficiency in the plants. In order to understand the expression pattern of HPT, a 946 bp DNA upstream fragment of the Arabidopsis HPT gene was isolated and transcriptionally fused with the β-glucuronidase （GUS） reporter gene, and the promoter-GUS cassette was introduced into Arabidopsis thaliana by Agrobacterium-mediated transformation. Analysis of transgenic plants by histochemical staining showed that the GUS gene was expressed predominantly in the roots, and also to a lesser degree, in adult leaves, fdament, and pistil, but not in stems, root tips, anthers, seeds, and siliqua. The results suggest that the HPT gene is predominantly expressed in Arabidopsis roots.