In plants, the deoxy sugar l-rhamnose is widely present as rhamnose-containing polymers in cell walls and as part of the decoration of various specialized metabolites. Here, we review the current knowledge on the distribution of rhamnose, highlighting the differences between what is known in dicotyledoneuos compared to commelinid monocotyledoneous (grasses) plants. We discuss the biosynthesis and transport of UDP-rhamnose, as well as the transfer of rhamnose from UDP-rhamnose to various primary and specialized metabolites. This is carried out by rhamnosyltransferases, enzymes that can use a large variety of substrates. Some unique characteristics of rhamnose synthases, the multifunctional enzymes responsible for the conversion of UDP-glucose into UDP-rhamnose, are considered, particularly from the perspective of their ability to convert glucose present in flavonoids. Finally, we discuss how little is still known with regards to how plants rescue rhamnose from the many compounds to which it is linked, or how rhamnose is catabolized.

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评论：植物中的鼠李糖——从生物合成到多种功能

在植物中，脱氧糖 L-鼠李糖广泛存在于细胞壁中作为含鼠李糖的聚合物，并作为各种特殊代谢物的装饰的一部分。在这里，我们回顾了目前关于鼠李糖分布的知识，强调了双子叶植物与单子叶植物（草）植物相比，已知的双子叶植物之间的差异。我们讨论了 UDP-鼠李糖的生物合成和运输，以及鼠李糖从 UDP-鼠李糖向各种初级和特化代谢物的转移。这是由鼠李糖基转移酶进行的，这种酶可以使用多种底物。鼠李糖合酶的一些独特特征，负责将 UDP-葡萄糖转化为 UDP-鼠李糖的多功能酶，被认为，特别是从它们转化类黄酮中存在的葡萄糖的能力的角度来看。最后，我们讨论了关于植物如何从与其相关的许多化合物中拯救鼠李糖，或鼠李糖如何分解代谢的知识知之甚少。