Momonoki Y S
Faculty of Bioindustry, Tokyo University of Agriculture, Abashiri, Japan.
Plant Physiol. 1997 May;114(1):47-53. doi: 10.1104/pp.114.1.47.
Acetylcholinesterase (AChE) activity has previously been studied by this laboratory and shown to occur at the interface between the stele and cortex of the mesocotyl of maize (Zea mays L.) seedlings. In this work we studied the distribution of AChE activity in 5-d-old maize seedlings following a gravity stimulus. After the stimulus, we found an asymmetric distribution of the enzyme in the coleoptile, the coleoptile node, and the mesocotyl of the stimulated seedlings using both histochemical and colorimetric methods for measuring the hydrolysis of acetylthiocholine. The hydrolytic capability of the esterase was greater on the lower side of the horizontally placed seedlings. Using the histochemical method, we localized the hydrolytic capability in the cortical cells around the vascular stele of the tissues. The hydrolytic activity was inhibited 80 to 90% by neostigmine, an inhibitor of AChE. When neostigmine was applied to the corn kernel, the gravity response of the seedling was inhibited and no enzyme-positive spots appeared in the gravity-stimulated seedlings. We believe these results indicate a role for AChE in the gravity response of maize seedlings.
本实验室之前对乙酰胆碱酯酶（AChE）活性进行了研究，结果表明其存在于玉米（Zea mays L.）幼苗中胚轴的中柱和皮层之间的界面处。在这项研究中，我们研究了重力刺激后5日龄玉米幼苗中AChE活性的分布情况。刺激后，我们使用组织化学和比色法测量乙酰硫代胆碱的水解，发现受刺激幼苗的胚芽鞘、胚芽鞘节和中胚轴中该酶分布不对称。水平放置的幼苗下侧酯酶的水解能力更强。使用组织化学方法，我们将水解能力定位在组织维管束周围的皮层细胞中。新斯的明（一种AChE抑制剂）可使水解活性受到80%至90%的抑制。当将新斯的明应用于玉米粒时，幼苗的重力反应受到抑制，且在受重力刺激的幼苗中未出现酶阳性斑点。我们认为这些结果表明AChE在玉米幼苗的重力反应中发挥作用。
