Comparative genomics reveals the molecular basis of the synthesis of triterpenoid saponin and distinct flower morphology in Sapindaceae species. Cardiospermum halicacabum

Sapindaceae, also named as soapberry family, is a large family of plants of great morphological diversities. Some have petal-less flowers, some bear fruits with fleshy arils, and some are great source of certain secondary metabolites, like saponins. With the fast development of next generation sequencing technologies, a number of Sapindaceae species have their genome sequenced, providing great resources for research from the perspective of comparative genomics. Here, we sequenced a high-quality genome of balloon-vine (Cardiospermum halicacabum L.), the first liana plant with a full-genome sequenced in Sapindaceae, with the smallest genome size reported so far. Low heterozygosity and short life cycle confer it a great potential to become an ideal model plant for functional genomics research in Sapindaceae. In order to annotation of balloon-vine and further comparative analyses of Sapindaceae, relevant tissues were collected for transcriptome sequencing. Our work provides new insight and a great demonstration of using comparative genomics to dissect the molecular basis of characteristic trait development in Sapindaceae.