College of Pharmacy, Henan University of Chinese Medicine, Zhengzhou 450046, China.
National Nanfan Research Institute (Sanya), Chinese Academy of Agricultural Sciences, Sanya 572024, China.
Genes (Basel). 2024 Jan 24;15(2):155. doi: 10.3390/genes15020155.
, a member of the Scrophulariaceae family, has been widely used in traditional Chinese medicine since ancient times. The main bioactive component of is catalpol. However, the biogenesis of catalpol, especially its downstream pathway, remains unclear. To identify candidate genes involved in the biosynthesis of catalpol, transcriptomes were constructed from using the young leaves of three cultivars, Beijing No. 3, Huaifeng, and Jin No. 9, as well as the tuberous roots and adventitious roots of the Jin No. 9 cultivar. As a result, 71,142 unigenes with functional annotations were generated. A comparative analysis of the transcriptomes identified over 200 unigenes of 13 enzymes potentially involved in the downstream steps of catalpol formation, including 9 genes encoding UGTs, 13 for aldehyde dehydrogenases, 70 for oxidoreductases, 44 for CYP450s, 22 for dehydratases, 30 for decarboxylases, 19 for hydroxylases, and 10 for epoxidases. Moreover, two novel genes encoding geraniol synthase (RgGES), which is the first committed enzyme in catalpol production, were cloned from . The purified recombinant proteins of RgGESs effectively converted GPP to geraniol. This study is the first to discover putative genes coding the tailoring enzymes mentioned above in catalpol biosynthesis, and functionally characterize the enzyme-coding gene in this pathway in . The results enrich genetic resources for engineering the biosynthetic pathway of catalpol and iridoids.
地黄是玄参科植物，自古以来就是中国传统医学的重要组成部分。地黄的主要生物活性成分为梓醇。然而，梓醇的生物合成途径，尤其是其下游途径，仍不清楚。为了鉴定参与梓醇生物合成的候选基因，我们使用三个品种（北京 3 号、怀风和金 9 号）的幼叶以及金 9 号的块根和不定根构建了 的转录组。结果生成了 71142 个具有功能注释的 unigenes。对 转录组的比较分析鉴定了超过 200 个潜在参与梓醇形成下游步骤的 13 种酶的 unigenes，包括 9 个编码 UGTs 的基因、13 个醛脱氢酶基因、70 个氧化还原酶基因、44 个 CYP450s 基因、22 个脱水酶基因、30 个脱羧酶基因、19 个羟化酶基因和 10 个环氧化酶基因。此外，我们还从 中克隆了两个编码香叶醇合酶（RgGES）的新基因，RgGES 是梓醇生物合成的第一个关键酶。纯化的 RgGES 重组蛋白有效地将 GPP 转化为香叶醇。本研究首次在梓醇生物合成中发现了上述修饰酶的假定基因，并对该途径中的酶编码基因进行了功能表征。研究结果丰富了梓醇和环烯醚萜类生物合成途径工程的遗传资源。
