Lu Xu, Yang Hua, Liu Xinguang, Shen Qian, Wang Ning, Qi Lian-Wen, Li Ping
State Key Laboratory of Natural Medicines, China Pharmaceutical UniversityNanjing, China.
Plant Biotechnology Research Center, School of Agriculture and Biology, Shanghai Jiao Tong UniversityShanghai, China.
Front Plant Sci. 2017 May 26;8:872. doi: 10.3389/fpls.2017.00872. eCollection 2017.
The most unique components of extracts are terpene trilactones (TTLs) including ginkgolides and bilobalide. Study of TTLs biosynthesis has been stagnant in recent years. Metabolic profiling of 40 compounds, including TTLs, flavonoids, and phenolic acids, were globally analyzed in leaf, fibrous root, main root, old stem and young stem extracts of . Most of the flavonoids were mainly distributed in the leaf and old stem. Most of phenolic acids were generally distributed among various tissues. The total content of TTLs decreased in the order of the leaf, fibrous root, main root, old stem and young stem. The TTLs were further analyzed in different parts of the main root and old stem. The content of TTLs decreases in the order of the main root periderm, the main root cortex and phloem and the main root xylem. In old stems, the content of TTLs in the cortex and phloem was much higher than both the old stem periderm and xylem. The expression patterns of five key genes in the ginkgolide biosynthetic pathway were measured by real-time quantitative polymerase chain reaction (RT-Q-PCR). Combining metabolic profiling and RT-Q-PCR, the results showed that the fibrous root and main root periderm tissues were the important biosynthesis sites of ginkgolides. Based on the above results, a model of the ginkgolide biosynthesis site and transport pathway in was proposed. In this putative model, ginkgolides are synthesized in the fibrous root and main root periderm, and these compounds are then transported through the old stem cortex and phloem to the leaves.
提取物中最独特的成分是萜类三内酯（TTLs），包括银杏内酯和白果内酯。近年来，TTLs生物合成的研究一直停滞不前。对银杏叶、须根、主根、老茎和幼茎提取物中的40种化合物（包括TTLs、黄酮类化合物和酚酸）进行了代谢谱分析。大多数黄酮类化合物主要分布在叶片和老茎中。大多数酚酸普遍分布于各个组织中。TTLs的总含量按叶、须根、主根、老茎和幼茎的顺序递减。对主根和老茎的不同部位进一步分析了TTLs。TTLs的含量按主根周皮、主根皮层和韧皮部以及主根木质部的顺序递减。在老茎中，皮层和韧皮部中TTLs的含量远高于老茎周皮和木质部。通过实时定量聚合酶链反应（RT-Q-PCR）测定了银杏内酯生物合成途径中五个关键基因的表达模式。结合代谢谱分析和RT-Q-PCR，结果表明须根和主根周皮组织是银杏内酯的重要生物合成部位。基于上述结果，提出了银杏内酯在银杏中的生物合成部位和转运途径模型。在这个推测模型中，银杏内酯在须根和主根周皮中合成，然后这些化合物通过老茎皮层和韧皮部运输到叶片。
