Integrative Analysis Of Multiple Metabolomes And Transcriptome Revealed Pigment Formation Mechanism In Red Skin Root Syndrome Of Panax Ginseng

Asia ginseng（Panax ginseng）is one of the most valuable medicinal herbs in China.Red skin root syndrome causes reduction of both production and quality of ginseng.The previous laboratory research found the color expression and pathogenesis of red skin root syndrome ginseng are closely related to the accumulation of phenolic substances.However,its development process and key metabolites are still unknown.Multiple metabolomes including non-targeted metabolome,and anthocyanins-targeted and carotenoids-targeted metabolomes were performed on field grown red skin and healthy ginseng.The detected metabolites were analyzed in combination with previous transcriptome results.Further clarify the reasion of red skin root syndrome ginsen color expression,the main results as follows:1.Compared with healthy ginseng,red skin root syndrome ginseng showed red to brown color in epidermis and the fibrous roots are significantly reduced.The red to brown color was only constrainted for section analysis of the fibril roots ginsengs,found red skin root syndrome ginseng’s cell layers are red;2.Using untargeted metabolome analysis,red skin root syndrome / healthy ginseng skin were found to include different concentrations of many compounds.Citric acid and ginsenoside Rc,Rg5 are reduced in red skin root syndrome ginseng,and asmonic acid（JA）,12-oxygen-plant dienic acid（OPDA）,coumarin,2-hydroxycinnamic acid,quinic acid and pantothenic acid are increased 5-70 times in the red skin root syndrome ginseng;3.By the anthocyanins and carotenoid targeted metabolome analysis,red skin root syndrome ginseng showed higher concentrations of β-carotene,α-carotene,rutin,chalone,anthocyanins pigment than healthy ginseng;4.By transcriptome reanalysis of red skin root syndrome / healthy ginseng epidermis,the changes of metabolites involved in the anthocyanin synthesis pathway were found to relate to the expression of genes.Consistently,the expressions of 17 MYB transcription factors were differentially regulated in red skin root syndrome ginseng.,JA related cis-elements are widely distributed at their promoters.Based on the tight association of anthocyanins and carotenoid accumulation with MYB transcription factors,it is speculated that MYB transcription factors of JA signal pathway were supposed to mediate accumulation of anthocyanins and carotenoids that contributed to the development of red skin root syndrome ginseng.In conclusion,red skin root syndrome ginseng showed red to brown color in the upper several cell layersin epidermis which showd obvious change in both primary metabolism such as citrate and secondary metabolites such as coumarin,and anthocyanins and carotenoid content.Combined with transcriptome speculated that MYB transcription factor can regulate JA signaling pathway affect anthocyanins and carotenoid accumulation,thus contributing to the color expression of red skin root syndrome ginseng.