The chromosome-level genome of double-petal phenotype jasmine provides insights into the biosynthesis of floral scent

Jasmine (Jasminum sambac Aiton) is a well-known cultivated plant species for its fragrant flowers used in the perfume industry and cos-metics. However, the genetic basis of its floral scent is largely unknown. In this study, using PacBio, Illumina, 10x Genomics and high-throughput chromosome conformation capture (Hi-C) sequencing technologies, a high-quality chromosome-level reference genome for J. sambac was obtained, exploiting a double-petal phenotype cultivar 'Shuangbanmoli' (JSSB). The results showed that the final assembled genome of JSSB is 580.33 Mb in size (contig N50 = 1.05 Mb; scaffold N50 = 45.07 Mb) with a total of 39 618 predicted protein-coding genes. Our analyses revealed that the JSSB genome has undergone an ancient whole-genome duplication (WGD) event at 91.68 million years ago (Mya). It was estimated that J. sambac diverged from the lineage leading to Olea europaea and Osmanthus fragrans about 28.8 Mya. On the basis of a combination of genomic, transcriptomic and metabolomic analyses, a range of floral scent volatiles and genes were identified involved in the benzenoid/phenylpropanoid and terpenoid biosynthesis pathways. The results provide new insights into the molecular mechanism of its fragrance biosynthesis in jasmine.