Unland Kristina, Pütter Katharina M, Vorwerk Kirsten, van Deenen Nicole, Twyman Richard M, Prüfer Dirk, Schulze Gronover Christian
Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) Muenster Germany.
Institute of Plant Biology and Biotechnology University of Muenster Muenster Germany.
Plant Direct. 2018 Jun 13;2(6):e00063. doi: 10.1002/pld3.63. eCollection 2018 Jun.
The Russian dandelion produces high-value isoprenoids such as pentacyclic triterpenes and natural rubber in the latex of specialized cells known as laticifers. Squalene synthase (SQS) and squalene epoxidase (SQE) catalyze key steps in the biosynthesis of cyclic terpenoids, but neither enzyme has yet been characterized in . Genomic analysis revealed the presence of two genes ( and ) encoding isoforms of SQS, and four genes () encoding isoforms of . Spatial expression analysis in different tissues confirmed that TkSQS1 and TkSQE1 are the latex-predominant isoforms, with highly similar mRNA expression profiles. The TkSQS1 and TkSQE1 proteins colocalized in the endoplasmic reticulum membrane and their enzymatic functions were confirmed by in vitro activity assays and yeast complementation studies, respectively. The functions of TkSQS1 and TkSQE1 were further characterized in the latex of plants with depleted or mRNA levels, produced by RNA interference. Comprehensive expression analysis revealed the coregulation of and , along with a downstream gene in the triterpene biosynthesis pathway encoding the oxidosqualene cyclase TkOSC1. This indicates that the coregulation of , and could be used to optimize the flux toward specific terpenoids during development.
俄罗斯蒲公英在称为乳管的特化细胞的乳胶中产生高价值的类异戊二烯,如五环三萜和天然橡胶。鲨烯合酶(SQS)和鲨烯环氧酶(SQE)催化环状萜类生物合成中的关键步骤,但这两种酶在[此处缺失具体物种信息]中均未得到表征。基因组分析揭示了存在两个编码SQS同工型的基因([此处缺失基因名称]和[此处缺失基因名称]),以及四个编码[此处缺失具体酶名称]同工型的基因([此处缺失基因名称])。在不同[此处缺失组织类型信息]组织中的空间表达分析证实,TkSQS1和TkSQE1是乳胶中占主导的同工型,具有高度相似的mRNA表达谱。TkSQS1和TkSQE1蛋白共定位于内质网膜,并且它们的酶功能分别通过体外活性测定和酵母互补研究得到证实。通过RNA干扰产生的[此处缺失具体植物名称]植物乳胶中,TkSQS1和TkSQE1的功能在[此处缺失具体基因名称]或[此处缺失具体基因名称]mRNA水平降低的情况下得到进一步表征。综合表达分析揭示了[此处缺失具体基因名称]和[此处缺失具体基因名称]以及三萜生物合成途径中一个编码氧化鲨烯环化酶TkOSC1的下游基因的共调控。这表明[此处缺失具体基因名称]、[此处缺失具体基因名称]和[此处缺失具体基因名称]的共调控可用于在发育过程中优化特定萜类的通量。