The Analysis Of Metabolism Of Phenolic Compounds In Red Skin Root And Its Relationship With Disease Occurrence

Panax Ginseng, a member of the family Araliaceae ginseng,and perennial herbs,is an expensive Chinese medicine, has a long history in China. Ginseng industry is thedominant characteristic resources industry in Jilin Province, an important economicpillar industry of the Changbai Mountains area.Ginseng can not be continuouslycropped at the same land,the continuously cropping ginseng seedlings suivial rate isabout25%in the3years old ginseng soil. Thus, farmer has to deforest to cultivateginseng at Changbai moutains, which resulted in a great loss of forestresources,destroying forest ecological balance and soil erosion.The red-skin rootdisease of ginseng is an indispensable factor of the continuous cropping barrier onginseng cultivation. It’s a physiological phenomena, generally occured in the processof cultivation.Our previous work found that: with ginseng red-skin root disease isclosely correlated with the disolution of active aluminum in soil by increasing soil.Multifactors including aluminum toxicity induces the increase of phenoliccompoundsand then oxidizationin ginseng epidermal to form red precipitation. Andginseng will also activate antioxidative system to alleviate phenoloxidation.Considering the close correlation between ginseng red skin root diseasesand accumulation and oxidation of phenolic compounds,this study focus on thephysiological and biochemical,and molecular level research about phenolicsmetabolism and oxidation, and antioxidative system in red skin root disease,The mainresults are as follows:More total phenolic compounds accumulation was found at the epidermal tissue ofred skin root disease ginseng compared to the healthy ones. The contents of lignin andanthocyanin content was also analysised but no significant difference was found at theepidermal tissues between the red skin and healthy ginsengsWe analysized the activities of enzymes and transcriptional level of their encoding genes involving inbiosynthesis of the phenolic compounds in both healthy and red skin root disesseginsengs. the red skin ginseng higher activities of glucose6phosohate(G6PDH),shikimate dehydrogenase (SKDH),phenylalanine annmonia-lyase(PAL), cinnamate4-hydroxylase(C4H), which related to biosysnthesis ofphenolic compounds closely, as well as caffeic acidO-methyltransferase(COMT),caffeoyl-CoAO-methyltransferase(CCOMT),4-coumarate:CoA ligase(4CL), Anthocyanidinsynthase (ANS), Flavonoid3′,5′-hydroxylase (F35H), Chalcone isomerase (CHI),Dihydroflavonol reductase (DFR),UDP-flavonoid glucosyltransferase(UFGT) relatedto the biosynthesis of lignin anthocyanin. The transcriptional level of gene putativelyencoding these enzymes was also up-regulated at the red skin root disease ginseng.While enzyme activities and transcription levels of Flavonol synthase (FLS),Isoflavone O-methyl-transferase (IOMT), Isoflavone2′-hydroxylase (I2H) whichrelated to flavone and isoflavone biosynthase was decreased and downregulated at theepidermal of red skin compared with healthy ginseng. Higher activities andtranscriptional expression was also found at red root epidermal with antioxidativesystems enzymes polyphenol oxidase(PPO),Peroxidase(POD),superoxidedismutase(SOD),catalase(CAT), glutathione peroxide(GPX),glutathionesynthase(GS),glutathione reductase(GR) and their putatively endoding genes.In the field experiment, exogenous application of AsAand Ca2+succeeded toalleviate the red skin root disease indices in a three years old ginseng field., whichsupports the view that the occurrence of red skin root disease related closely to theoxidation of phenolic compounds.