The chromosome-scale reference genome of Rubus chingii Hu provides insight into the biosynthetic pathway of hydrolysable tannins.
Rubus chingii Hu (Fu-Pen-Zi), a perennial woody plant in the Rosaceae family, is a characteristic traditional Chinese medicinal plant because of its unique pharmacological effects. There are abundant hydrolysable tannin (HT) components in R. chingii that provide health benefits. Here, an R. chingii chromosome-scale genome and related functional analysis provide insights into the biosynthetic pathway of HTs. Sequence data totaling 231.21 Mb (155 scaffolds with an N50 of 8.2 Mb) were assembled into seven chromosomes with an average length of 31.4 Mb, and 33130 protein-coding genes were predicted, 89.28% of which were functionally annotated. Evolutionary analysis showed that R. chingii was most closely related to R. occidentalis, from which it was predicted to have diverged 22.46 million years ago. Comparative genomic analysis showed that there was a tandem gene cluster of UGT, CXE and SCPL genes on chromosome 02 of R. chingii, including 11 CXE, 8 UGT, and 6 SCPL genes, which may be critical for the synthesis of HTs. In vitro enzyme assays indicated that the proteins encoded by the CXE (LG02.4273) and UGT (LG02.4102) genes have tannin hydrolase and gallic acid glycosyltransferase functions, respectively. The genomic sequence of R. chingii will be a valuable resource for comparative genomic analysis within the Rosaceae family and will be useful for understanding the biosynthesis of HTs.