Brandle J E, Telmer P G
Southern Crop Protection and Food Research Center, 1391 Sandford Street, London, Ont., Canada N5V 4T3.
Phytochemistry. 2007 Jul;68(14):1855-63. doi: 10.1016/j.phytochem.2007.02.010. Epub 2007 Mar 29.
Steviol glycosides are found in high concentrations in the leaves of the Paraguayan perennial herb Stevia rebaudiana and their intense sweetness, as well as high concentration in Stevia leaf tissue, has made them the subject of research interest for over 100 years. Steviol glycosides are diterpenoids whose biosynthetic pathways share four steps in common with gibberellic acid formation. The convergence of genomics and plant biochemistry has led to the rapid elucidation of the genes coding for the various enzymes in the biosynthetic pathway. Functional characterization of the enzymes coded for by those genes is on-going. The first committed step in the pathway is the synthesis of the aglycone steviol and the various glycosides found in the leaf tissue result from the elaboration of steviol by a number of glucosyltransferases.
甜菊糖苷在巴拉圭多年生草本植物甜叶菊的叶子中含量很高，其极高的甜度以及在甜叶菊叶片组织中的高浓度，使其成为100多年来研究的热点。甜菊糖苷是二萜类化合物，其生物合成途径与赤霉素的形成有四个共同步骤。基因组学和植物生物化学的结合使得生物合成途径中各种酶的编码基因得以迅速阐明。对这些基因编码的酶的功能表征正在进行中。该途径的第一个关键步骤是苷元甜菊醇的合成，叶片组织中发现的各种糖苷是由多种糖基转移酶对甜菊醇进行修饰而成的。
