The chromosome-scale assembly of endive (Cichorium endivia) genome provides insights into the sesquiterpenoid biosynthesis

Endive (Cichorium endivia L.) is a leafy vegetable in the Asteraceae family. Sesquiterpene lactones (STLs) in endive leaves bring a bitter taste that varies between varieties. Despite their importance in breeding varieties with unique flavours, sesquiterpenoid biosynthesis pathways in endive are poorly understood. We assembled a chromosome-scale endive genome of 641 Mb with a contig N50 of 5.16 Mb and annotated 46,711 protein-coding genes. Several gene families, especially terpene syntheses (TPS) genes, expanded significantly in the C. endivia genome. STLs biosynthesis-related genes and TPS genes in more bitter varieties have shown a higher level of expression, which could be attributed to genomic variations. Our results penetrate the origin and diversity of bitter taste and facilitate the molecular breeding of endive varieties with unique bitter tastes. The high-quality endive assembly would provide a reference genome for studying the evolution and diversity of Asteraceae.

Automated summary

In this study, we assembled a chromosome-scale endive genome and annotated a large number of protein-coding genes. It was found that gene families related to sesquiterpenoid biosynthesis expanded significantly in the endive genome. Furthermore, genes related to sesquiterpenoid biosynthesis and terpene synthases were expressed at higher levels in more bitter varieties, possibly due to genomic variations. These findings contribute to our understanding of the origin and diversity of bitter taste, and provide a molecular basis for breeding endive varieties with unique bitter tastes.