小麦根尖细胞分化过程中木质素合成及其相关酶的活性变化

小麦（Triticumaestivum）根尖细胞分化过程中，苯丙氨酸解氨酶PAL．EC4．3．1．5]和对香豆酸辅酶A联结酶4CL，EC6．2．1．12]的活性从分生区至成熟区逐渐增加．PAL活性在分生区细胞中为0.4CL活性近似为0．在成熟区细胞中PAL和4CL活性均增加到最大．木质素的含量变化与PAL和4CL活性存在着平行性，同样在分生区细胞中木质素含量很低，到伸长区稍许增加，至成熟区增加最多．PAL和4CL是木质素合成的开始步骤和关键酶．木质素主要在管状分子和细胞壁次生加厚时沉积，是细胞分化的重要标志之一．

Changes in enzymatic activity during the period of cell differentiation of wheat (Triticum aestivum) root tip

Activity of enzymes PAL and 4CL during the period of cell differentiation of wheat root tip increased coordinately from the meristem region to the mature region. Activity of PAl. and 4CL was maximum in the mature region. The activity of PAL was zero in the meristem region and that of 4CL was nearly to zero in the meristem region. Some parallel relationships among lignin content, the activities of PAL and 4CL were revealed. Lignin content was the minimum in the meristem region, then increased slightly from the meristem region to the elongation region. The content in the mature region reached maximum. The further experiments indicated that there were sequential relations among PAL, 4CL activities and lignin content. PAl. and 4CL were the initial and key enzymes in the process of Lignin synthesis. Then the I.ignin mainly deposited on the secondary wall of the tracheary-element.It was in accord with the fundamental rule that the material metabolism is always established prior to the morphogenesis.