Genome assembly and annotation of the medicinal plant Calotropis gigantea, a producer of anticancer and antimalarial cardenolides

Calotropis gigantea produces specialized secondary metabolites known as cardenolides which have anti-cancer and anti-malarial properties. Although transcriptomic studies have been conducted in other cardenolide-producing species, no nuclear genome assembly for an Asterid cardenolide-producing species has been reported to date. A high quality de novo assembly was generated for C. gigantea, representing 157,284,427 bp with an N50 scaffold size of 805,959 bp, for which quality assessments indicated a near complete representation of the genic space. Transcriptome data in the form of RNA-sequencing libraries from a developmental tissue series was generated to aid in annotation and construction of a gene expression atlas. Using an ab initio and evidence-driven gene annotation pipeline, 18,197 high confidence genes were annotated. Homologous and syntenic relationships between C. gigantea and other species within the Apocynaceae family confirmed previously identified evolutionary relationships ...

牛角瓜（Calotropis gigantea）可产生一类名为强心甾烯（cardenolides）的特化次级代谢产物，该类物质兼具抗癌与抗疟活性。尽管学界已在其他产强心甾烯的物种中开展了转录组学研究，但截至目前，尚无关于菊类（Asterid）产强心甾烯物种的核基因组组装的相关报道。本研究针对牛角瓜构建了高质量的从头组装（de novo assembly）基因组，组装序列总长达157,284,427 bp，支架N50长度达805,959 bp；质量评估结果显示，该组装几乎完整覆盖了基因空间。为辅助基因注释与基因表达图谱的构建，本研究额外生成了覆盖一系列发育阶段组织的RNA测序（RNA-sequencing）文库转录组数据。通过结合从头预测（ab initio）与证据驱动的基因注释流程，本研究共注释得到18,197个高置信度基因。通过分析牛角瓜与夹竹桃科（Apocynaceae）其他物种间的同源与共线性关系，验证了此前已揭示的演化关系……