Deletion and tandem duplications of biosynthetic genes drive the diversity of triterpenoids in Aralia elata

• Published in: Nature communications Vol. 13; no. 1; pp. 2224 - 16
• Main Authors: Wang, Yu, Zhang, He, Ri, Hyok Chol, An, Zeyu, Wang, Xin, Zhou, Jia-Nan, Zheng, Dongran, Wu, Hao, Wang, Pengchao, Yang, Jianfei, Liu, Ding-Kun, Zhang, Diyang, Tsai, Wen-Chieh, Xue, Zheyong, Xu, Zhichao, Zhang, Peng, Liu, Zhong-Jian, Shen, Hailong, Li, Yuhua
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.04.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 45/23; 45/91; 631/208/212/2304; 631/449/2667; 631/45/603; 631/61/318; Aralia - metabolism; Aralia elata; Araliaceae; Callus; Chromosomes; Complementation; Divergence; Exons; Gene sequencing; Genes; Genomes; Humanities and Social Sciences; multidisciplinary; Panax; Panax - metabolism; Reproduction (copying); Saponins; Saponins - genetics; Science; Science (multidisciplinary); Species; Synthesis; Triterpene saponins; Triterpenes - metabolism; Triterpenoids
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-29908-y

Araliaceae species produce various classes of triterpene and triterpenoid saponins, such as the oleanane-type triterpenoids in Aralia species and dammarane-type saponins in Panax , valued for their medicinal properties. The lack of genome sequences of Panax relatives has hindered mechanistic insight into the divergence of triterpene saponins in Araliaceae. Here, we report a chromosome-level genome of Aralia elata with a total length of 1.05 Gb. The loss of 12 exons in the dammarenediol synthase (DDS)-encoding gene in A . elata after divergence from Panax might have caused the lack of dammarane-type saponin production, and a complementation assay shows that overexpression of the PgDDS gene from Panax ginseng in callus of A. elata recovers the accumulation of dammarane-type saponins. Tandem duplication events of triterpene biosynthetic genes are common in the A. elata genome, especially for AeCYP72As , AeCSLMs , and AeUGT73s , which function as tailoring enzymes of oleanane-type saponins and aralosides. More than 13 aralosides are de novo synthesized in Saccharomyces cerevisiae by overexpression of these genes in combination. This study sheds light on the diversity of saponins biosynthetic pathway in Araliaceae and will facilitate heterologous bioproduction of aralosides. Unlike Panax species, which can produce dammarane-type saponins, Aralia elata can only synthesize oleananetype saponins. Here, the authors reveal that the loss of the dammaranediol synthase-encoding gene and tandem duplication of triterpene biosynthetic genes drive structural divergences of saponins between the two genera.