Ficker M, Kirch H H, Eijlander R, Jacobsen E, Thompson R D
Max Planck Institute für Züchtungsforschung, Cologne, Germany.
Mol Gen Genet. 1998 Jan;257(2):132-42. doi: 10.1007/s004380050632.
A functional analysis of the promoter of the S2-RNase gene from potato was performed in transgenic potato and tobacco plants, using a deletion series of S2-RNase promoter GUS fusions. A detailed histochemical and quantitative analysis of the transgenic tobacco plants revealed that S2 promoter fragments ranging in size from 5.6 kb in length down to 0.2 kb mediate a weak developmentally regulated expression in the pistil, and strong ectopic expression in pollen. In the pistil, different expression patterns were seen depending on the transformant, the predominant one being characterized by expression in the stigma and the transmitting tract of the style, whereas a few plants showed expression exclusively either in the stigma or in the stylar transmitting tissue. All transformants also showed GUS expression in the placental epidermis of the ovary. Two sequences that are conserved between the potato S1-RNase and S2-RNase promoters, termed motif and motif III, are located in a fragment of the S2 promoter extending from position of -200 to bp -100, and motif II, located between by -498 and -480, was identified on the basis of sequence comparisons between pistil-specific promoters. Motif II was found to be dispensible for pistil-specific and for pollen-specific expression. Two submotifs, A and B, were identified with the motif I. Both were essential for expression in the pistil but only B was necessary for expression in pollen. Although motif III has a similar bipartite structure and sequence to motif I, it was not sufficient to confer-either pollen- or pistil-specific expression. However, deletion of motif III abolished pollen-specific expression in transient expression experiments, suggesting that an interaction between the two sequence motifs may be needed to specify cell type-specific expression. In transgenic potato the S2-RNase promoter also mediates expression in pollen and in the pistil; however, significantly fewer plants showed expression than in tobacco, with most plants also exhibiting GUS expression in other issues.
利用S2-RNase启动子GUS融合基因的缺失系列，在转基因马铃薯和烟草植株中对马铃薯S2-RNase基因的启动子进行了功能分析。对转基因烟草植株进行的详细组织化学和定量分析表明，长度从5.6 kb到0.2 kb的S2启动子片段介导雌蕊中弱的发育调控表达以及花粉中的强异位表达。在雌蕊中，根据转化体的不同观察到不同的表达模式，主要模式的特征是在柱头和花柱的传递组织中表达，而少数植株仅在柱头或花柱传递组织中表达。所有转化体在子房的胎座表皮中也显示出GUS表达。马铃薯S1-RNase和S2-RNase启动子之间保守的两个序列，分别称为基序I和基序III，位于S2启动子从-200 bp到-100 bp的片段中，而位于-498到-480之间的基序II是根据雌蕊特异性启动子之间的序列比较确定的。发现基序II对于雌蕊特异性和花粉特异性表达是可有可无的。基序I鉴定出两个亚基序A和B。两者对于雌蕊中的表达都是必需的，但只有B对于花粉中的表达是必需的。尽管基序III与基序I具有相似的二分结构和序列，但它不足以赋予花粉或雌蕊特异性表达。然而，在瞬时表达实验中删除基序III消除了花粉特异性表达，这表明可能需要两个序列基序之间的相互作用来指定细胞类型特异性表达。在转基因马铃薯中，S2-RNase启动子也介导花粉和雌蕊中的表达；然而，显示表达的植株明显少于烟草，大多数植株在其他组织中也表现出GUS表达。
