Phylogenomic elucidation of withanolide biosynthesis in Nightshade plants

薇甘内酯是茄属植物中的特殊代谢物，具有很强的抗增殖活性，作为传统药物，它具有悠久的人类使用历史。到目前为止，已分离出700多个天然内酯，其中许多代表具有生物活性。然而，人们对这些结构多样的类固醇内酯是如何在植物中合成的知之甚少。在前期工作中，我们通过对所有公开可用的基因组和转录组数据的分析，确定了一个可能的胡萝卜内酯生物合成基因簇。在这个项目中，在一个植物生物化学小组和一个生物信息学小组之间的合作的基础上，我们想要探索这一假说，并利用它来阐明木兰素内酯的生物合成的系统基因组学。具体地说，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胡萝卜素内酯亚类的进化，我们将对胡萝卜素内酯生产者Withan ia Somnifera、Datura Innoxiia和Nicandra Physalodes的另外三个基因组进行测序。从这个序列数据中，我们将根据可能负责结构亚类产生的共性、系统发育关系和共表达来选择和评估候选基因。基于测序数据和通过这种方法获得的生物合成基因，我们将能够重建木兰素内酯及其不同亚类的进化历史。因此，我们的项目将提供对胡芦巴内酯生物合成的分子基础和进化的基本见解。从长远来看，这些发现将有助于更好地利用这种结构多样的天然产品类别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.