Sato Y, Watanabe T, Komamine A, Hibino T, Shibata D, Sugiyama M, Fukuda H
Biological Institute, Faculty of Science, Tohoku University, Sendai, Japan.
Plant Physiol. 1997 Feb;113(2):425-30. doi: 10.1104/pp.113.2.425.
Changes in the enzymatic activity of cinnamyl alcohol dehydrogenase (CAD) and in the expression of a gene for CAD during tracheary element (TE) differentiation were investigated in cultures of single cells isolated from the mesophyll of zinnia (Zinnia elegans). In cultures in which TE differentiation was induced (TE-inductive cultures), CAD activity increased from h 36 after the start of culture (12 h before the start of thickening of the secondary cell wall) and peaked at h 72, when lignin was actively being deposited. In control cultures in which TE differentiation was not induced, CAD activity remained at a very low level for 5 d. Some isoforms of CAD were detected only in the TE-inductive cultures by native gel electrophoresis and subsequent staining for CAD activity. A cDNA clone for CAD, ZCAD1, was isolated from Z. elegans using a cDNA clone for CAD from Aralia cordata as the probe. RNA gel-blot analysis revealed that in the TE-inductive cultures the level of ZCAD1 mRNA increased from h 36 and peaked at h 48 to 60. No such increases were observed in control cultures. These results indicated that both the gene expression and the activity of CAD are strictly regulated, in association with lignification, during TE differentiation in Z. elegans.
在从百日草（Zinnia elegans）叶肉中分离出的单细胞培养物中，研究了肉桂醇脱氢酶（CAD）的酶活性变化以及CAD基因在管状分子（TE）分化过程中的表达情况。在诱导TE分化的培养物（TE诱导培养物）中，CAD活性从培养开始后36小时（次生细胞壁加厚开始前12小时）开始增加，并在72小时达到峰值，此时木质素正在积极沉积。在未诱导TE分化的对照培养物中，CAD活性在5天内一直保持在非常低的水平。通过非变性凝胶电泳和随后的CAD活性染色，仅在TE诱导培养物中检测到一些CAD同工型。以刺五加的CAD cDNA克隆为探针，从百日草中分离出CAD的cDNA克隆ZCAD1。RNA凝胶印迹分析表明，在TE诱导培养物中，ZCAD1 mRNA水平从36小时开始增加，并在48至60小时达到峰值。在对照培养物中未观察到这种增加。这些结果表明，在百日草的TE分化过程中，CAD的基因表达和活性都与木质化相关，受到严格调控。
