The camphor tree genome enhances the understanding of magnoliid evolution.

Magnoliids represent the third largest branch of the most diverse and species-rich angiosperms,and their phylogenetic position rela-tive to monocots and eudicots remains uncertain(Dong et al.,2021).Here,we describe the assembly of a high-quality chromo-some-level genome sequence for Cinnamomum camphora(camphor),an evergreen tree belonging to Lauraceae.Genome-based phylogenetic analysis indicated possible incomplete lineage sorting(ILS)during the rapid diversification of the early diverging branches of angiosperms,which may have led to the unstable phylo-genetic position of magnoliids.Whole-genome duplication(WGD)analysis showed that the lineage leading to C.camphora experi-enced two WGD events:the earlier event was shared by the common ancestor of Chimonanthus salicifolius and Lauraceae,and the more recent event was shared by all lineages of Lauraceae.The ABCDE homolog genes of C.camphora showed broad expression in floral or-gans,revealing the molecular mechanism preventing tepals from differentiating into petals and sepals.The key genes for the synthesis of monoterpenes have been identified,and the molecular regulatory mechanism underlying the rich essential oils in the branches and leaves has been revealed.Overall,our study provides a better under-standing of the evolution and diversification of magnoliids and the evolution of floral organs.