玉米ZmBRI1基因的克隆、表达及功能分析

油菜素内酯(BRs)是一种重要的甾族类激素,在植物的生长过程中起着重要的作用。本研究利用同源克隆的方法,从玉米B73自交系中获得了一个新的油菜素内酯受体蛋白编码基因ZmBRI1,该基因全长为3369 bp,编码1122个氨基酸。亚细胞定位分析表明,ZmBRI1蛋白定位于细胞膜上,而且ZmBRI1在各个玉米的各个组织器官中都有表达,其中在幼嫩的组织中表达最高。利用转基因技术将ZmBRI1导入BR不敏感突变体bri1-5中,获得的转基因植株修复了其表型,特别是植株高度、叶片形态和果荚大小。与突变体bri1-5比较,油菜素内酯(brassinolide,BL)处理显著抑制转基因株系根系生长;丙环唑(propiconazole,Pcz)处理显著抑制了下胚轴生长;同时转基因株系DWF4和CPD基因的表达量下降。此外,在野生型(Ws)中过表达ZmBRI1,显著提高了拟南芥在ABA抑制条件下的种子萌发率和植株生长,下调了ABA响应基因RD29A、RD29B、ABI5和RAB18的表达。因此,ZmBRI1不仅参与了植物的形态建成和BR的信号传导,而且参与调控了植物对ABA信号的响应。

Cloning,Expression and Functional Analysis of Brassinosteroid Receptor Gene (ZmBRI1) from Zea MaysL.

Brassinosteroids (BRs) isone of very important plant steroidal hormones that are essential in a wide variety of physiological processes. In this study, an encoding brassinosteroid receptorhomologous gene was cloned by homology cloning from maizeB73 inbred lines, and designated as ZmBRI1. Sequence analysis revealed that the full length of ZmBRI1 was 3369bp, encoding 1122 amino acids. Moreover,ZmBRI1 protein was localized in cell membrane by the protein subcellular localization analysis and a ubiquitously expressed receptor kinase expressed highly in young tissues. The transformation ofZmBRI1 into the Arabidopsis dwarf mutant bri1-5 restored the phenotype, including plant height, leaf morphology and pod size. Compared to bri1-5, Brassinolide (BL) inhibited significantly the root growth of transgenic lines,and Propiconazole(Pcz) inhibited the hypocotyl growth, and the expression levels of DWF4 and CPD were decreased in the transgenic plants. Furthermore, with ABA treatment, overexpression of ZmBRI1 in wild type increased the germination rate and plant growth, and decreased the expression of ABA downstream genes RD29A, RD29B, ABI5,and RAB18 compared to wild type. Therefore, ZmBRI1 was not only involved in plant morphogenesis and BR signal transduction, but also played a pivotal role in response to ABA signal.