AMMONIA-REGULATED EXPRESSION OF A SOYBEAN GENE ENCODING CYTOSOLIC GLUTAMINE-SYNTHETASE IN TRANSGENIC LOTUS-CORNICULATUS
AMMONIA-REGULATED EXPRESSION OF A SOYBEAN GENE ENCODING CYTOSOLIC GLUTAMINE-SYNTHETASE IN TRANSGENIC LOTUS-CORNICULATUS
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DOI：
10.1105/tpc.3.1.11
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发表时间：
1991-01-01
期刊：
影响因子：
11.6
通讯作者：
VERMA, DPS
中科院分区：
文献类型：
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作者：
MIAO, GH;HIREL, B;VERMA, DPS
通过直接互补大肠杆菌gln A突变体，获得了一个编码胞质谷氨酰胺合成酶（GS）的全长cDNA克隆，该基因在大豆根和根瘤中表达。 这一顺序是诱导根氨的可用性。 分离对应于该cDNA的基因组克隆（GS15）的3.5-脱氢酶启动子片段，并将其与报告基因[β-葡萄糖醛酸酶（GUS）]融合。 通过农杆菌介导的转化将GS-GUS融合体导入豆科植物（百脉根）和非豆科植物（烟草）植物中。 该嵌合基因在烟草和L. corniculatus，表达仅限于生长的根尖和成熟根的维管束。 用氨处理增加了该嵌合基因在豆类背景中的表达（即，L. corniculatus）;然而，在烟草根中没有观察到诱导。 氨处理转基因L. corniculatus根在所有细胞类型中表现出均匀分布。 这些数据表明，大豆胞质GS基因的组织特异性在烟草和L。然而，在后一种情况下，该基因是氨诱导的。 此外，氨处理还促进了L. corniculatus是由于转录的增加。 GS-GUS在感染区（包括未感染细胞）和转基因L. corniculatus结节，其中氨的通量是由这个组织遇到。 GS-GUS在结节的外皮层中表达的缺乏表明氨可能不能扩散到内皮层之外。
A full-length cDNA clone encoding cytosolic glutamine synthetase (GS), expressed in roots and root nodules of soybean, was isolated by direct complementation of an Escherichia coli gln A- mutant. This sequence is induced in roots by the availability of ammonia. A 3.5-kilobase promoter fragment of a genomic clone (lambda-GS15) corresponding to this cDNA was isolated and fused with a reporter [beta-glucuronidase (GUS)] gene. The GS-GUS fusion was introduced into a legume (Lotus corniculatus) and a nonlegume (tobacco) plant by way of Agrobacterium-mediated transformations. This chimeric gene was found to be expressed in a root-specific manner in both tobacco and L. corniculatus, the expression being restricted to the growing root apices and the vascular bundles of the mature root. Treatment with ammonia increased the expression of this chimeric gene in the legume background (i.e., L. corniculatus); however, no induction was observed in tobacco roots. Histochemical localization of GUS activity in ammonia-treated transgenic L. corniculatus roots showed a uniform distribution across all cell types. These data suggest that the tissue specificity of the soybean cytosolic GS gene is conserved in both tobacco and L. corniculatus; however, in the latter case, this gene is ammonia inducible. Furthermore, the ammonia-enhanced GS gene expression in L. corniculatus is due to an increase in transcription. That this gene is directly regulated by externally supplied or symbiotically fixed nitrogen is also evident from the expression of GS-GUS in the infection zone, including the uninfected cells, and the inner cortex of transgenic L. corniculatus nodules, where a flux of ammonia is encountered by this tissue. The lack of expression of GS-GUS in the outer cortex of the nodules suggests that ammonia may not be able to diffuse outside the endodermis.