Elicitation And Antioxidant Activity Of Phenolics In Cell Suspension Culture Of Jerusalem Artichoke Tuber

Jerusalem artichoke(Helianthus tuberosus L.)is a perennial herb of Asterceae and Helianthus L.,commonly known as foreign ginger,ground-ring.Jerusalem artichoke has a wide range of ecological adaptability,which can grow in the barren soil,with frost and plant disease resistance.Jerusalem artichoke contains phenolic substances,which have important physiological functions,and it has been widely used in food,medicine and other industries,but the related studies are limited to Jerusalem artichoke leaves and tuberous tissue.In this study,plant tissue culture technology was used to establish the cell suspension culture of Jerusalem artichoke tubers,and selected three kinds of biological elicitors(methyl jasmonate,salicylic acid and yeast extract)to induce the suspension culture of Jerusalem artichoke tubers,the effects of three kinds of biological elicitors on the total phenolic content were analyzed,the qualitative and quantitative analysis of these phenolics and its changing in the cell suspension culture of Jerusalem artichoke were identified by ultra performance liquid chromatography with 14 kinds of standard phenolic compounds.In addition,the antioxidant activities of total phenolics in cell suspension culture were studied by ABTS,DPPH and FRAP methods.This study provided a theoretical basis for the large-scale industrial production of secondary metabolites such as phenols by using cell suspension culture of Jerusalem artichoke.The results showed as below:(1)Growth kinetics of cell suspension culture of Jerusalem artichokeThe callus was induced by tuber of Jerusalem artichoke and used for the cell suspension culture.The callus was induced by MS solid medium with hormone ratio of 1.0 mg/L NAA and1.0 mg/L 6-BA,30 g/L sucrose and 7.5 g/L agar,the growth curve of the suspension cell was studied by suspension culture of Jerusalem artichoke,tubers was induced by MS solid medium with hormone ratio of 1.0 mg/L NAA and 3.0 mg/L 6-BA and 30 g/L sucrose,the amount of cells inoculated was 4 g/100 mL,which entered the logarithmic phase on the 9th day,the cell biomass reached the maximum on the 24 th day and entered the recession after the 33 rd day.(2)Elicitation of phenolics in cell suspension culture of Jerusalem artichoke tubers by three different inducersThe optimum concentration of yeast extract was 0.5 mg/L(4.92 mg GAE/g DW),the optimal concentration of salicylic acid was 50 ?mol/L(2.33 mg GAE/G DW),the best treatment concentration of methyl jasmonate was 200 ?mol/L(7.39 mg GAE/g DW,the total phenol content was 1.52 times of the control group).The optimum treatment time of the yeast extract was on the 3rd day(4.65 mg GAE/g DW),the best treatment time of salicylic acid was on 12 th days(4.61 mg GAE/g DW),the optimum treatment time for methyl jasmonate was on12 th days(10.85 mg GAE/g DW,total phenol content was 2.88 times of the control group).10 phenolic compounds were detected in the suspension cells of Jerusalem artichoke by ultra performance liquid chromatography and liquid-mass spectrometry(protocatechuic acid,4-hydroxybenzoic acid,chlorogenic acid,caffeic acid,catechins,epicatechin,scopolamine,3-hydroxycinnamic acid,erucic acid,quercetin).The content of quercetin in the suspension cells of Jerusalem artichoke elicited by methyl jasmonate was 2.56 times higher than that of the control group.The contents of catechin and chlorogenic acid were 7.6 and 6 times,respectively.The content of 4-hydroxybenzoic acid remained same,compared with the control group,the other six kinds of phenolic methyl jasmonate treatment group had lower content,the protocatechuic acid was not detected in the control group.(3)Antioxidant activity of phenolics in cell suspension culture of Jerusalem artichoke tuberIn this study,the antioxidant activities of total phenolics in cell suspension culture of Jerusalem artichoke were evaluated by FRAP,DPPH and ABTS.The removal rate of ABTS reached the maximum in the suspension cells of Jerusalem artichoke,which was 39.63%,and the free radical scavenging rate of ABTS in the control group was 14.25%.The DPPH scavenging rate was the highest,which was 42.13%,while the DPPH free radical scavenging rate in the control group was only 10.22%.The antioxidant capacity of FRAP was elicited by methyl jasmonate in the suspension cells of Jerusalem artichoke,which reached 7.12 mg TE/g DW,while the FRAP antioxidant capacity of the control group was only 2.29 mg TE/g DW.(4)Comparison of phenolic content and composition and antioxidant activity of suspension cells of tubers and stemsThe content of total phenol in suspension cells of Jerusalem artichoke tubers was compared with that of suspension cells of stems,the effect of yeast extract on cell suspension of tubers(total phenol content reached 4.65 mg GAE/g DW)was significantly higher than that of cell suspension of stems(total phenol content reached 3.63 mg GAE/g DW),especially the total phenolic content in the suspension cells of tubers induced by methyl jasmonate was(total phenol content reached 10.85 mg GAE/g DW)significantly higher than that in the suspension cells of stems(total phenol content reached 5.52 mg GAE/g DW),with an increase of 0.97 times.Compared with the suspension cells of stems,the content of catechins and quercetin(the content reached 1.53 mg GAE/g DW and 5.58 mg GAE/g DW)were significantly higher than those of the suspension cells of stems(the content reached 1.1 mg GAE/g DW and 3.94 mg GAE/g DW),while the content of 4-hydroxybenzoic acid and chlorogenic acid in the suspension cells of tubers(the content reached 0.37 mg GAE/g DW and 0.23 mg GAE/g DW)induced by methyl jasmonate was significantly lower than that of the suspension cells of stems(the content reached 0.84 mg GAE/g DW and 1.06 mg GAE/g DW).The free radicalscavenging ability of ABTS and DPPH and the antioxidant capacity of FRAP were higher than that of the control group,and the suspension cells of tubers were higher than those of the suspension cells of stems.