Li Y, Hagen G, Guilfoyle T J
Department of Biochemistry, University of Missouri, Columbia 65211.
Dev Biol. 1992 Oct;153(2):386-95. doi: 10.1016/0012-1606(92)90123-x.
An auxin-inducible bidirectional promoter from the soybean SAUR gene locus was fused to a reporter gene in one direction and a cytokinin biosynthetic gene in the opposite direction and the expression of these fused genes was examined in transgenic tobacco. The Escherichia coli uidA gene, which encodes the enzyme beta-glucuronidase (GUS), was used as the reporter gene and the Agrobacterium tumefaciens ipt gene, which encodes the enzyme isopentenyl transferase, was used as the cytokinin biosynthetic gene. These constructs allowed the overproduction of cytokinins in tobacco in a tissue- and organ-specific manner. Localized overproduction of cytokinins was monitored using the GUS reporter gene and measured by an ELISA assay. The tissue- and organ-specific overproduction of cytokinins produced a number of morphological and physiological changes, including stunting, loss of apical dominance, reduction in root initiation and growth, either acceleration or prolonged delayed senescence in leaves depending on the growth conditions, adventitious shoot formation from unwounded leaf veins and petioles, altered nutrient distribution, and abnormal tissue development in stems. While some of these morphological changes result directly from the localized overproduction of cytokinins, other changes probably result from the mobilization of plant nutrients to tissues rich in cytokinins.
将来自大豆SAUR基因座的生长素诱导型双向启动子在一个方向上与报告基因融合，在相反方向上与细胞分裂素生物合成基因融合，并在转基因烟草中检测这些融合基因的表达。编码β-葡萄糖醛酸酶（GUS）的大肠杆菌uidA基因用作报告基因，编码异戊烯基转移酶的根癌农杆菌ipt基因用作细胞分裂素生物合成基因。这些构建体使烟草中细胞分裂素以组织和器官特异性方式过量产生。使用GUS报告基因监测细胞分裂素的局部过量产生，并通过ELISA测定法进行测量。细胞分裂素在组织和器官中的特异性过量产生导致了许多形态和生理变化，包括发育迟缓、顶端优势丧失、根起始和生长减少、根据生长条件叶片衰老加速或延迟延长、未受伤的叶脉和叶柄形成不定芽、养分分布改变以及茎中组织发育异常。虽然其中一些形态变化直接源于细胞分裂素的局部过量产生，但其他变化可能是由于植物养分向富含细胞分裂素的组织中转移所致。
