Insights into salvianolic acid B biosynthesis from chromosome-scale assembly of the Salvia bowleyana genome

Salvia bowleyanais a traditional Chinese medic-inal plant that is a source of nutritional supple-ments rich in salvianolic acid B and a potentialexperimental system for the exploration ofsalvianolic acid B biosynthesis in the Labiatae.Here,we report a high‐quality chromosome‐scalegenome assembly of S.bowleyana covering 462.44 Mb,with a scaffold N50 value of 57.96 Mband 44,044 annotated protein‐coding genes.Evolutionary analysis revealed an estimateddivergence time betweenS.bowleyanaand its close relativeS.miltiorrhiza of~3.94 millionyears.We also observed evidence of a whole‐genome duplication in theS.bowleyanagenome.Transcriptome analysis showed that SbPAL1(PHENYLALANINE AMMONIA‐LYASE1)ishighlyexpressed in roots relative to stem and leaves,paralleling the location of salvianolic acid Baccumulation.The laccase gene family in S.bowley anaoutnumbered their counterparts inbothS.miltiorrhiza and Arabidopsis thaliana,suggesting that the gene family has undergoneexpansion inS.bowleyana.Several laccasegenes were also highly expressed in roots,wheretheir encoded proteins may catalyze the oxida-tive reaction from rosmarinic acid to salvianolicacid B.Thesefindings provide an invaluable ge-nomic resource for understanding salvianolicacid B biosynthesis and its regulation,and will beuseful for exploring the evolution of the Labiatae.