Rai Mayank, He Chengkun, Wu Ray
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
Transgenic Res. 2009 Oct;18(5):787-99. doi: 10.1007/s11248-009-9263-2. Epub 2009 Apr 9.
To identify minimal effective promoters for driving abiotic stress-inducible transgene expression in rice, we selected promoter elements of three stress-responsive genes, viz. rab16A coding for dehydrin, OsABA2 coding for zeaxanthin epoxidase, and a gene coding for a hypothetical protein (HP1) based on the presence of ABA-, salt- and drought-responsive cis-acting elements. These were translationally fused to the gusA reporter gene and introduced into rice to study their effect on heterologous gene expression. The OsABA2 promoter was found to be the most effective and desirable promoter among the three in terms of driving a low constitutive transgene expression under normal conditions and high induction in response to ABA, salt and drought stress, the highest being a 12-fold induction in response to ABA. The rab16A and HP1 promoters resulted in high levels of constitutive expression. While induction of GUS activity was generally two- to threefold for all the treatments in roots for both the promoters, induction in leaves was generally insignificant, the exceptions being rab16A in response to continuous salt stress and HP1 in response to water deficit. It was also observed that the three promoters, in general, resulted in lower constitutive expression, but higher induction in roots as compared to leaves.
为了鉴定驱动水稻非生物胁迫诱导型转基因表达的最小有效启动子，我们基于脱落酸（ABA）、盐和干旱响应顺式作用元件的存在，选择了三个胁迫响应基因的启动子元件，即编码脱水蛋白的rab16A、编码玉米黄质环氧化酶的OsABA2以及一个编码假定蛋白（HP1）的基因。将这些启动子元件与gusA报告基因进行翻译融合，并导入水稻中，以研究它们对异源基因表达的影响。就正常条件下驱动低水平组成型转基因表达以及对ABA、盐和干旱胁迫的高诱导性而言，发现OsABA2启动子是这三个启动子中最有效且最理想的，对ABA的最高诱导倍数为12倍。rab16A和HP1启动子导致高水平的组成型表达。对于这两个启动子，在根中所有处理的GUS活性诱导通常为两到三倍，而在叶中诱导通常不显著，例外情况是rab16A对持续盐胁迫的响应以及HP1对水分亏缺的响应。还观察到，一般而言，这三个启动子导致较低的组成型表达，但与叶相比，在根中有更高的诱导性。
