Gene duplication is assumed to be the major force driving the evolution of metabolite biosynthesis in plants.Freed from functional burdens,duplicated genes can mutate toward novelties until fixed due to selective fitn...Gene duplication is assumed to be the major force driving the evolution of metabolite biosynthesis in plants.Freed from functional burdens,duplicated genes can mutate toward novelties until fixed due to selective fitness.However,the extent to which this mechanism has driven the diversification of metabolite biosynthesis remains to be tested.Here we performed comparative genomics analysis and functional characterization to evaluate the impact of gene duplication on the evolution of triterpenoid biosynthesis using Panax species as models.Wefound that whole-genome duplications(WGDs)occurred independently in Araliaceae and Apiaceae lineages.Comparative genomics revealed the evolutionary trajectories of triterpenoid biosynthesis in plants,which was mainly promoted by WGDs and tandem duplication.Lanosterol synthase(LAS)was likely derived from a tandemduplicate of cycloartenol synthase that predated the emergence of Nymphaeales.Under episodic diversifying selection,the LAS gene duplicates produced by g whole-genome triplication have given rise to triterpene biosynthesis in core eudicots through neofunctionalization.Moreover,functional characterization revealed that oxidosqualene cyclases(OSCs)responsible for synthesizing dammarane-type triterpenes in Panax species were also capable of producing ocotilloltype triterpenes.Genomic and biochemical evidence suggested that Panax genes encoding the above OSCs originated from the specialization of one OSC gene duplicate produced from a recent WGD shared by Araliaceae(Pg-b).Our results reveal the crucial role of gene duplication in diversification of triterpenoid biosynthesis in plants and provide insight into the origin of ocotillol-type triterpenes in Panax species.展开更多
基金supported by Digitalization of biological resources(202002AA100007)the Guangxi Innovation-Driven Development Project(GuiKe AA18242040)+1 种基金the General Project for Basic Research in Yunnan(grant no.202201AT070266)the National Natural Science Foundation of China(81860680)。
文摘Gene duplication is assumed to be the major force driving the evolution of metabolite biosynthesis in plants.Freed from functional burdens,duplicated genes can mutate toward novelties until fixed due to selective fitness.However,the extent to which this mechanism has driven the diversification of metabolite biosynthesis remains to be tested.Here we performed comparative genomics analysis and functional characterization to evaluate the impact of gene duplication on the evolution of triterpenoid biosynthesis using Panax species as models.Wefound that whole-genome duplications(WGDs)occurred independently in Araliaceae and Apiaceae lineages.Comparative genomics revealed the evolutionary trajectories of triterpenoid biosynthesis in plants,which was mainly promoted by WGDs and tandem duplication.Lanosterol synthase(LAS)was likely derived from a tandemduplicate of cycloartenol synthase that predated the emergence of Nymphaeales.Under episodic diversifying selection,the LAS gene duplicates produced by g whole-genome triplication have given rise to triterpene biosynthesis in core eudicots through neofunctionalization.Moreover,functional characterization revealed that oxidosqualene cyclases(OSCs)responsible for synthesizing dammarane-type triterpenes in Panax species were also capable of producing ocotilloltype triterpenes.Genomic and biochemical evidence suggested that Panax genes encoding the above OSCs originated from the specialization of one OSC gene duplicate produced from a recent WGD shared by Araliaceae(Pg-b).Our results reveal the crucial role of gene duplication in diversification of triterpenoid biosynthesis in plants and provide insight into the origin of ocotillol-type triterpenes in Panax species.
