Platycodon grandiflorus is a medicinal plant whose main component is platycodins, which have a variety of pharmacological effects and nutritional values. The farnesyl pyrophosphate synthase (FPS) is a key enzyme in the isoprenoid biosynthesis pathway, which catalyzes the synthesis of farnesyl diphosphate (FPP). In this study, we cloned the FPS gene from P. grandiflorus (PgFPS) with an ORF of 1260 bp, encoding 419 amino acids with a deduced molecular weight and theoretical pI of 46,200.98 Da and 6.52, respectively. The squalene content of overexpressed PgFPS in tobacco leaves and yeast cells extract was 1.88-fold and 1.21-fold higher than that of the control group, respectively, and the total saponin content was also increased by 1.15 times in yeast cells extract, which verified the biological function of PgFPS in terpenoid synthesis. After 48 h of MeJA treatment and 6 h of ethephon treatment, the expression of the PgFPS gene in roots and stems reached its peak, showing a 3.125-fold and 3.236-fold increase compared to the untreated group, respectively. Interestingly, the expression of the PgFPS gene in leaves showed a decreasing trend after exogenous elicitors treatment. The discovery of this enzyme will provide a novel perspective for enhancing the efficient synthesis of platycodins.

中文翻译：

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桔梗法呢基焦磷酸合酶基因的克隆、表达特性及三萜类化合物合成功能鉴定


桔梗是一种药用植物，其主要成分为桔梗素，具有多种药理作用和营养价值。法呢基焦磷酸合酶（FPS）是类异戊二烯生物合成途径中的关键酶，催化法呢基二磷酸（FPP）的合成。在本研究中，我们克隆了大花凤梨的FPS基因（PgFPS），其ORF为1260 bp，编码419个氨基酸，推导分子量和理论pI分别为46,200.98 Da和6.52。过表达的PgFPS在烟叶和酵母细胞提取物中的角鲨烯含量分别比对照组高1.88倍和1.21倍，酵母细胞提取物中总皂苷含量也增加1.15倍，验证了PgFPS 在萜类化合物合成中的生物学功能。 MeJA处理48 h和乙烯利处理6 h后，根和茎中PgFPS基因的表达量达到峰值，分别比未处理组增加3.125倍和3.236倍。有趣的是，经过外源诱导子处理后，叶片中PgFPS基因的表达量呈现下降趋势。该酶的发现将为增强桔梗皂苷的高效合成提供新的视角。