Samaj J, Hawkins S, Lauvergeat V, Grima-Pettenati J, Boudet A
UMR CNRS/UPS 5546, Centre de Biologie et Physiologie Végétales, Université Paul Sabatier, Toulouse, France.
Planta. 1998 Apr;204(4):437-43. doi: 10.1007/s004250050277.
Cinnamyl alcohol dehydrogenase 2 (CAD 2) localization and the cell-specific activity of the eucalyptus CAD 2 promoter were investigated by CAD 2 immunogold localization and promoter beta-glucuronidase (GUS) histochemistry in apical and mature parts of stable transformed poplar (Populus tremula x P. alba) stems. Both CAD 2 protein and GUS activity were found to be confined in the same types of cells in the shoot apices, particularly in the determined meristematic cells in leaf axils and shell zones, procambium and developing tracheids. Within mature stems, CAD 2 and GUS were also identified in cambium and in fully or partially lignified cells derived from it (young xylem, developing phloem fibres, chambered parenchyma cells around phloem). Additionally, GUS activity was found in the scale leaves of apical shoot buds and in the roots (namely in the procambium, cambium, phellogen, young xylem, pericycle) of transformed plants. By employing immunogold cytochemistry, CAD 2 was shown to be localized in the cytoplasm within cambial, ray and young xylem cells in stems, the gold particles being randomly attached to endoplasmic reticulum and Golgi-derived vesicles. These results support a crucial role for CAD 2 in lignification and indicate a new role for this enzyme in branching events within the shoot apex and during lateral root formation.
通过在稳定转化的杨树（Populus tremula x P. alba）茎尖和成熟部位进行肉桂醇脱氢酶2（CAD 2）免疫金定位和启动子β-葡萄糖醛酸酶（GUS）组织化学，研究了CAD 2的定位以及桉树CAD 2启动子的细胞特异性活性。结果发现，CAD 2蛋白和GUS活性均局限于茎尖的相同类型细胞中，特别是叶腋和壳区的已确定分生细胞、原形成层和发育中的管胞。在成熟茎中，CAD 2和GUS也存在于形成层以及由其衍生的完全或部分木质化细胞（幼嫩木质部、发育中的韧皮纤维、韧皮部周围的腔室薄壁细胞）中。此外，在转化植株的顶芽鳞片叶和根中（即原形成层、形成层、木栓形成层、幼嫩木质部、中柱鞘）也发现了GUS活性。通过免疫金细胞化学方法，显示CAD 2定位于茎中形成层、射线和幼嫩木质部细胞的细胞质中，金颗粒随机附着在内质网和高尔基体衍生的囊泡上。这些结果支持了CAD 2在木质化过程中的关键作用，并表明该酶在茎尖分支事件和侧根形成过程中具有新的作用。
