Lourdes Miranda-Ham María de, Islas-Flores Ignacio, Vázquez-Flota And Felipe
From the Unidad de Bioquímica y Biología Molecular de Plantas, and the Graduate Program in Plant Sciences and Biotechnology, Centro de Investigación Científica de Yucatán, Calle 43 No. 130, Chuburná de Hidalgo, 97200 Mérida, Yucatán, México.
Biochem Mol Biol Educ. 2007 May;35(3):206-10. doi: 10.1002/bmb.60.
Alkaloids are part of the chemical arsenal designed to protect plants against an adverse environment. Therefore, their synthesis and accumulation are frequently induced in response to certain environmental conditions and are mediated by chemical signals, which are formed as the first responses to the external stimulus. A set of experiments using Catharanthus roseus seedlings is presented to illustrate this interaction. Using the well characterized induction of monoterpenoid indole alkaloid synthesis in response to methyl jasmonate, one chemical mediator; simple and reproducible experiments are proposed to demonstrate this type of plant-environment interaction to plant physiology or biochemistry B.Sc. students. After exposure to the inducer, seedlings are analyzed for alkaloid accumulation and for the increase of tryptophan decarboxylase (TDC) enzyme activity by means of thin layer chromatography, followed by UV spectrophotometry. Alkaloids should increase as a result of the exposure to the inducer, as well as TDC activity, which plays a critical role in channeling carbon skeletons from primary to secondary metabolism in this plant.
生物碱是植物用于抵御不利环境的化学防御武器的一部分。因此，它们的合成和积累常常因特定环境条件而被诱导，并由化学信号介导，这些化学信号是对外部刺激的第一反应。本文展示了一组使用长春花幼苗的实验来说明这种相互作用。利用已充分表征的茉莉酸甲酯诱导单萜吲哚生物碱合成这一化学介质，提出了简单且可重复的实验，向植物生理学或生物化学专业的本科学生展示这种植物 - 环境相互作用。在接触诱导剂后，通过薄层色谱法分析幼苗的生物碱积累情况以及色氨酸脱羧酶（TDC）酶活性的增加，随后进行紫外分光光度法测定。由于接触诱导剂，生物碱以及TDC活性都应增加，TDC在该植物中将碳骨架从初级代谢导向次级代谢的过程中起着关键作用。
