Tokunaga Naohito, Uchimura Nami, Sato Yasushi
Department of Biology, Faculty of Science, Ehime University, Matsuyama, Japan.
Protoplasma. 2006 Sep;228(4):179-87. doi: 10.1007/s00709-006-0180-4. Epub 2006 Sep 20.
Gibberellin (GA) is considered an important growth regulator involved in many aspects of plant development. However, little is known about the relationship between GA and lignification. In this study, we analyzed the role of GA in tracheary element (TE) differentiation and lignification using a Zinnia elegans xylogenic culture. When gibberellic acid-3 (GA3) was exogenously supplied, a slight increase in the frequency of TE differentiation and a remarkable increase in lignin content were observed. Computer image analysis of individual TEs showed that the lignification level of each TE was significantly increased in the culture treated with GA3 compared with those of the control. In contrast, suppression of TE differentiation and lignification was observed when GA biosynthesis was inhibited by ancymidol, paclobutrazol, or uniconazole. This suppression was restored by the addition of GA3. These results suggest that GA plays an important role in TE differentiation, and even more so in lignification. When conditioned medium obtained after 120 h of control culture was analyzed by high-performance liquid chromatography, many lignin precursors were detected. However, these lignin precursors were greatly reduced in the GA-treated culture. This result suggests that GA promotes lignification by activating the polymerization of lignin precursors.
赤霉素（GA）被认为是一种重要的生长调节剂，参与植物发育的许多方面。然而，关于GA与木质化之间的关系却知之甚少。在本研究中，我们利用百日草木质化培养体系分析了GA在管状分子（TE）分化和木质化中的作用。当外源供应赤霉酸-3（GA3）时，观察到TE分化频率略有增加，木质素含量显著增加。对单个TE进行计算机图像分析表明，与对照相比，用GA3处理的培养物中每个TE的木质化水平显著提高。相反，当用嘧啶醇、多效唑或烯效唑抑制GA生物合成时，观察到TE分化和木质化受到抑制。添加GA3可恢复这种抑制作用。这些结果表明，GA在TE分化中起重要作用，在木质化中作用更显著。当通过高效液相色谱分析对照培养120小时后获得的条件培养基时，检测到许多木质素前体。然而，在GA处理的培养物中，这些木质素前体大大减少。这一结果表明，GA通过激活木质素前体的聚合来促进木质化。
