Phylogenomic elucidation of withanolide biosynthesis in Nightshade plants

Withanolides是龙葵属植物的特殊代谢物，具有有效的抗增殖活性，作为传统药物在人类中有着悠久的使用历史。迄今为止已分离出700多种天然金皂素，其中许多代表具有生物活性。然而，这些结构多样的甾体内酯是如何在植物中合成的，我们知之甚少。在初步工作中，我们通过分析所有可公开获得的威纳醇内酯生产者的基因组和转录组数据，确定了一个假定的威纳醇内酯生物合成基因簇。在这个项目中，建立在植物生物化学小组和生物信息学小组之间的合作基础上，我们希望探索这一假设，并利用它来阐明威纳醇内酯生物合成的系统基因组。具体来说，我们将通过异源表达和病毒诱导的基因沉默来验证我们已经确定的候选基因。此外，为了进一步了解不同的Withania olides亚类的进化，我们将对Withania somnifera， Datura innoxia和Nicandra physalodes的三个额外的Withania olides基因组进行测序。从这些序列数据中，我们将根据可能导致结构亚类产生的同属性、系统发育关系和共表达来选择和评估候选基因。基于序列数据和通过这种方法获得的生物合成基因，我们将能够重建皂苷类及其不同亚类的进化史。因此，我们的项目将为糖醇内酯生物合成的分子基础和进化提供基本的见解。从长远来看，这些发现将有助于更好地利用这类结构多样的天然产物的药用特性进行药物开发。

Withanolides are specialised metabolites from Nightshade plants with potent antiproliferative activity, which possess a long history of human usage as traditional medicine. More than 700 natural withanolides have been isolated so far, and many representatives are biologically active. Little is known, however, how these structurally diverse steroidal lactones are synthesised in plants. In preliminary work, we identified a putative withanolide biosynthetic gene cluster by analysis of all publicly available genome and transcriptome data of withanolide producers. In this project, building on a collaboration between a plant biochemistry group and a bioinformatics group, we want to explore this hypothesis and leverage it for the phylogenomic elucidation of withanolide biosynthesis. Specifically, we will verify our already identified gene candidates by heterologous expression and virus-induced gene silencing. In addition, to further understand the evolution of different withanolide subclasses, we will sequence three additional genomes of the withanolide producers Withania somnifera, Datura innoxia and Nicandra physalodes. From this sequence data, we will select and evaluate gene candidates based on synteny, phylogenetic relationship, and co-expression that might be responsible for the generation of structural subclasses. Based on the sequence data and the biosynthetic genes gained by this approach, we will then be able to reconstruct the evolutionary history of withanolides and their different subclasses. Thus, our project will provide fundamental insights into the molecular basis and evolution of withanolide biosynthesis. On a long term, these findings will help to better harness the medicinal properties of this structurally varied natural product class for drug development.