Smith Alison G, Croft Martin T, Moulin Michael, Webb Michael E
Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
Curr Opin Plant Biol. 2007 Jun;10(3):266-75. doi: 10.1016/j.pbi.2007.04.009. Epub 2007 Apr 16.
Over recent years, the pathways for the biosynthesis of many vitamins have been elucidated at the molecular level in plants, and several unique features are emerging. One is that the mitochondrion plays an important role in the synthesis of folate (vitamin B9), biotin (B7), pantothenate (B5), ascorbate (C), and possibly thiamin (B1). Second, the production of some of these cofactors is regulated by developmental cues, and perhaps more surprisingly, by environmental signals such as high light and salinity. Moreover, the biosynthesis of thiamin in Arabidopsis may be negatively regulated by a riboswitch, a novel method of gene regulation that is characteristic of cofactor biosynthesis in bacteria. Vitamin B12 is unique in that it is not found in vascular plants, but is abundant in algae; recent molecular work has revealed that algae do not synthesise the vitamin but instead obtain it from bacteria.
近年来，许多维生素的生物合成途径已在植物的分子水平上得到阐明，一些独特的特征正在显现。其一，线粒体在叶酸（维生素B9）、生物素（B7）、泛酸（B5）、抗坏血酸（C）以及可能还有硫胺素（B1）的合成中发挥重要作用。其二，其中一些辅因子的产生受发育线索调控，或许更令人惊讶的是，还受高光和盐度等环境信号调控。此外，拟南芥中硫胺素的生物合成可能受核糖开关负调控，核糖开关是一种新型基因调控方式，是细菌辅因子生物合成的特征。维生素B12的独特之处在于它在维管植物中不存在，但在藻类中含量丰富；最近的分子研究表明，藻类并不合成这种维生素，而是从细菌中获取。
