玉米脱氧麦根酸分泌通道蛋白基因YS3启动子的克隆与启动活性分析

Cloning and promoter activity analyses of the promoter of 2'-deoxymugineic acid(DMA) secretion channel gene YS3 in maize

缺铁是世界范围内农业生产面临的严重问题,玉米通过分泌脱氧麦根酸(2’-deoxymugineic acid,DMA)吸收利用土壤中的难溶性铁。为探明玉米DMA分泌通道蛋白基因YS3的表达和调控机制,本文通过克隆获得长为2813 bp的YS3基因启动子,该序列含有大量TATA-box、CAAT-box等启动子基本元件,以及光响应、激素调控等多个顺式调控元件;构建YS3启动子驱动GUS基因的植物表达重组载体p CAMBIA-YS3GUS,利用农杆菌介导转化拟南芥,获得p YS3::GUS转基因植株,对转基因植株进行GUS组织化学染色,并通过石蜡切片技术对转基因植株进行组织观察,分析p YS3::GUS转基因植株中YS3基因启动子的活性。结果表明,YS3启动子主要驱动GUS基因在拟南芥根部表达,且主要集中在根部表皮细胞,机械损伤可激发YS3启动子活性,驱动GUS基因在损伤临近部位表达。本研究对于理解玉米DMA分泌的分子调控机理具有重要意义。

Iron （Fe） deficiency is a world-wide serious agricultural problem. Maize secretes 2＇-deoxymugineic acid （DMA） to uptake and utilize Fe from the soil. In order to explore the gene expression patterns of the DMA secre- tion channel gene YS3, we cloned the 2813 bp YS3 promoter, and constructed the plant expression vector pCAM-BIA-YS3GUS. The promoter contains a lot of TATA-boxes and CAAT-boxes, and cis-acting regulatory elements such as the light responsive elements and the hormone responsive elements. Arabidopsis was transformed via Agrobacte- rium tumefacients-mediated procedures to obtain the pYS3：：GUS transgenic plants, which were confirmed by GUS staining. Then, the stained tissue was observed using paraffin section methods and the YS3 promoter activity was also analyzed. We found that the promoter could drive GUS gene expression specifically in the root epidermal ceils. Me- chanical damage could activate the promoter, and drive the GUS gene expression adjacent to the damage sites. Our results provide a molecular basis to understand the DMA secretion process in maize.