Mechanism Of Biosynthesis Of Sesquiterpenes Volatile Oil In Atractylodes Lancea Under Different Light

There are differences between the artificial cultivation environment and the wild natural environment of Chinese herbal medicines.Some undergrowth and forest edge medical material have been placed in intensive cultivation in the open field,resulting in a lot of problems such as the ingredients of medical material are substandard,and Atractylodes lancea is a typical representative.Previous studies have shown that sesquiterpene volatile oil from Atractylodes lancea is susceptible to light,but the mechanism is unclear.This study sets different light intensity?CK,80%,60%,40%,20%,7%?and light quality?CK,red,blue,red-blue?9:1?,red-blue?6:1?,red-blue?3:1??experiments to study the dynamic regularity of the growth curve and sesquiterpene volatile oil in different light intensity and light quality of Atractylodes lancea,pigment content,photosynthetic parameters,antioxidant enzyme activity,hormones,and other physiological and biochemical indicators Changes and sesquiterpene synthesis of key enzyme gene expression.The main results as follows:The biomass and volatile oil accumulation of Atractylodes lancea under different light treatments are mainly during the expansion period.The root biomass?23.18 g,28.38 g?and the content of four volatile oil components?atractylodin,atractylodin,hinesol and?-eudesmol??3.74%and 5.17%?in the red-blue?9:1?group during the expansion and maturation stages of A.lancea,followed by the red-blue?6:1?group,the biomass is 18.32 g,25.15 g.The total amount of four volatile oils was 2.97%and 3.79%.The blue group has the lowest biomass and volatile oil content.In the light intensity group,the total biomass?14.52g,46.35g,59.56g?and volatile oil content?5.38%,6.95%,8.27%?of A.lancea under 80%light intensity were significantly higher than those of the control group during the whole growth period.With the weakening of light intensity,the biomass and volatile oil content gradually decreased.But 40%light intensity of volatile oil was slightly higher than that of the 60%light intensity group during the expansion and maturation stages.Photosynthetic parameters such as net photosynthetic rate,transpirationrate,stomatalconductanceandintercellularCO₂concentration under red-blue?9:1?light condition were higher than those of other treatment groups,and most of them had significant differences.In the red-blue?9:1?group,Chl?a+b?and Car have the highest content,and the ratio of Chla/b is also the highest.With the ratio decrease of the red light,the photosynthetic pigment relevant indicators also decreases,and the lowest pigment content of the blue group.The photosynthetic parameters of the 80%light intensity group were significantly higher than those in the control group,while the contents of Chl?a+b?and Car were the lowest.With the decrease of the light intensity,the Chl?a+b?and Car contents of Atractylodes lancea were also decreased.But the 80%light intensity group had the highest Chla/b ratio.Different light treatments had a significant effect on the antioxidant enzyme activity of Atractylodes lancea leaves.The activities of superoxide dismutase?SOD?,peroxidase?POD?,glutathione?GSH?,reduced ascorbic acid?AsA?and catalase?CAT?under different light quality were higher than those of the blank group,and most of them had significant differences;the content of malondialdehyde?MDA?in red-blue?9:1?light was significantly lower than that in the blank group.The antioxidant enzyme activity of 80%light intensity group was significantly lower than that of the control group.With the decrease of light intensity,the enzyme activity gradually increased,and there was no significant difference between the 60%light intensity group and the control group.The contents of jasmonic acid?JA?,salicylic acid?SA?,abscisic acid?ABA?,and gibberellin?GA3?in roots and leaves of A.lancea in red-blue?9:1?treatment group were significantly higher than those in the control group.The blue groups has the lowest levels of hormones.In the light intensity group,the content of hormone from 80%light intensity group in roots and leaves increased significantly compared with the control group,and with the weakening of light intensity,the plant hormone content gradually decreased,of which the content of root hormone under 40%light intensity group is slightly higher than 60%light intensity group.The expression levels of key enzyme genes DXR,HMGR,FPPS,and TPS were significantly higher in the red-blue?9:1?than those in the control group.And the expression levels of the related enzymes in the blue light group were the lowest.The expression content of the key enzyme genes in the 80%light intensity group were also significantly higher than those in the control group,and the lower the light intensity was,the lower the expression level was.The expression of key enzyme genes in the 40%light intensity group was slightly higher than that in the 60%light intensity group.The above results indicate that red-blue?9:1?light conditions and80%light intensity treatment are most suitable for the accumulation of biomass and secondary metabolites in Atractylodes lancea.