Gaudin V, Jouanin L
Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, Versailles, France.
Plant Mol Biol. 1995 Apr;28(1):123-36. doi: 10.1007/BF00042044.
Plant oncogenes aux1 and aux2 carried by the TR-DNA of Agrobacterium rhizogenes strain A4 encode two enzymes involved in the auxin biosynthesis pathway in transformed plant cells. The short divergent promoter region between the two aux-coding sequences contains the main regulatory elements. This region was fused to the uidA reporter gene and introduced into Nicotiana tabacum in order to investigate the regulation and the tissue specificity of these genes. Neither wound nor hormone induction could be detected on transgenic leaf discs. However, phytohormone concentration and auxin/cytokinin balance controlled the expression of the chimaeric genes in transgenic protoplasts. The expression was localised in apical meristems, root tip meristems, lateral root primordia, in cells derived from transgenic protoplasts and in transgenic calli. Histological analysis showed that the expression was located in cells reactivated by in vitro culture. Experiments using cell-cycle inhibitors such as hydroxyurea or aphidicolin on transgenic protoplast cultures highly decreased the beta-glucuronidase activity of the chimaeric genes. These results as well as the histological approach suggest a correlation between expression of the aux1 and aux2 genes and cell division.
发根农杆菌A4菌株的TR-DNA携带的植物致癌基因aux1和aux2编码转化植物细胞中生长素生物合成途径所涉及的两种酶。两个生长素编码序列之间的短差异启动子区域包含主要调控元件。该区域与uidA报告基因融合，并导入烟草中，以研究这些基因的调控和组织特异性。在转基因叶盘上未检测到伤口诱导或激素诱导。然而，植物激素浓度和生长素/细胞分裂素平衡控制了转基因原生质体中嵌合基因的表达。表达定位于顶端分生组织、根尖分生组织、侧根原基、源自转基因原生质体的细胞和转基因愈伤组织中。组织学分析表明，表达位于通过体外培养重新激活的细胞中。在转基因原生质体培养物上使用细胞周期抑制剂如羟基脲或阿非迪霉素的实验大大降低了嵌合基因的β-葡萄糖醛酸酶活性。这些结果以及组织学方法表明aux1和aux2基因的表达与细胞分裂之间存在相关性。
