The Populus koreana genome provides insights into the biosynthesis of plant aroma

Populus koreana is a tree species that shows unique fragrance traits because of the emission of volatiles from tissues, thus it has great potential for the study of aroma in forest trees. The genome of P. koreana, with a size of 429.47 Mb and N50 contigs of 4.97 Mb, was assembled into 19 chromosomes and 38,075 genes were predicted. P. koreana and Populus trichocarpa diverged from a common ancestor before 6.14 million years ago (Mya). Metabolome results suggested that the main aroma components terpenes and esters are significantly enriched in P. koreana leaves. Compared with that of P. trichocarpa, the P. koreana genome contains many more terpene synthase genes (TPSs), which encode proteins enriched in terpenoid-related metabolic pathways associated with the production of plant volatiles. Among these TPS genes, TPS-a/b might largely contribute to the synthesis of abundant sesquiterpenes and monoterpenes. Our results provide a valuable genomic resource for the further study of the production of aromatic volatiles by forest trees. Gene families related to terpenoid biosynthesis are substantially expanded in P. koreana, mainly resulting from tandem duplications and lineage specific whole-genome duplications. The evidence presented in this study increases our understanding of the evolution and diversity of plant volatile compounds, which could accelerate the selective breeding on traits of interest in Populus. The datasets of transcriptome and genome were uploaded in NCBI and China national center for bioinformation, respectively. The accession numbers were PRJCA012303, CRA012924, and PRJNA886606 (NCBI).