Studies On The Effects Of Mercury And Cadmium Stress On The Quality Of Atractylodes Lancea And Its Molecular Mechanism

Atractylodes lancea(Thunb.)DC.as a perennial herb of compositae,its rhizome has the effects of dampness and invigoration of spleen,dispels wind and disperses cold,and improves eyesight.It is a famous medicinal material in Jiangsu province,and is recognized as a high-quality Atractylodes lancea with definite curative effect and large clinical dosage.The main medicinal ingredients are sesquiterpene volatile oil,including β-eudesmol,atractylone and atractylodin.Due to the excessive heavy metals in the soil of original region,the growth and quality of Atractylodes lancea were greatly affected,and the quality and yield of medicinal materials were extremely unstable.This topic to the original region Atractylodes lancea as the research object,through the Atractylodes lancea under the stress of mercury,cadmium,physiological and biochemical indexes,efficacy composition and the change rule of key enzyme gene expression and its correlation,and under exogenous salicylic acid helps relieve the stress of mercury,cadmium Atractylodes lancea the change trend of physiological and biochemical indexes are studied,to reveal Atractylodes lancea under the stress of mercury,cadmium,art and molecular regulation mechanism,provide theoretical basis for the cogon grass green planting Atractylodes lancea.The main research contents and conclusions are as follows:(1)Study on the effects of mercury and cadmium stress on growth indexes and physiological indexes of Atractylodes ancea.At a low dose of 1 mg/kg of mercury and cadmium,the activity of antioxidant enzyme system(SOD,CAT and POD)in Atractylodes lancea was kept at a low level,malondialdehyde,proline and relative electrical conductivity were all at normal level,the growth potential of Atractylodes lancea was normal,and the development was not affected.When the mercury and cadmium stress concentrations were 10 mg/kg and 5 mg/kg respectively,the antioxidant enzyme activity and other indicators of Atractylodes lancea rose to the highest level.As the stress concentration continued to increase,the activity of SOD,CAT and POD showed a downward trend.The growth rate of Atractylodes lancea was slowed down,and its growth was inhibited.MDA,Pro and relative electrical conductivity of Atractylodes lancea were on the rise during the stress cycle.The higher the concentration,the faster the rise.(2)Effects of mercury and cadmium stress on photosynthetic fluorescence parameters of Atractylodes lancea.At the initial stage of stress,when the concentration of mercury and cadmium were 1 mg/kg,the heavy metal stimulated the photosynthetic ability of Atractylodes lancea,and the photosynthetic parameters Pn,Gs and Tr of the leaves showed a slight upward trend.With the extension of stress time,when the concentrations of mercury and cadmium continued to increase,the photosynthetic parameters all showed a downward trend.The fluorescence parameters F_v/F_m、F_v’/F_m’、qP、ETR and chlorophyll content all showed a decreasing trend with the increase of the stress concentration of mercury and cadmium in the stress cycle,while the value of qN showed a trend of slow rise and then decline.(3)Study on the effects of exogenous salicylic acid on alleviating physiological and biochemical indexes of Atractylodes lancea under the stress of mercury and cadmium.In this paper,mercury and cadmium were used to stress Atractylodes lancea under the concentration of 20 mg/kg,and then salicylic acid of different concentrations was irrigated.The results showed that salicylic acid could increase the activity of antioxidant enzymes,and decrease the MDA,Pro and relative electrical conductivity to alleviate the damage caused by stress.In terms of photosynthetic fluorescence,salicylic acid at a certain concentration can increase the chlorophyll content,increase the values of P_n、G_s、T_r、F_v/F_m、F_v’/F_m’、qP and ETR,and reduce the values of qN and Fo,indicating that salicylic acid can alleviate the harm caused by mercury and cadmium stress to the photosynthetic apparatus of Atractylodes lancea,and the effect is the best when the concentration is 1 mmol/L.(4)Study on the constituents of volatile oil from Atractylodes lancea under the stress of mercury and cadmium.In this paper,GC-MS method was used to analyze the volatile components of Atractylodes lancea under the stress of mercury and cadmium.With the increase of mercury and cadmium concentration,the volatile oil yield and components tended to decrease.The main components of volatile oil of Atractylodes lancea under the stress of mercury and cadmium were relatively similar,and the individual components of different gradients were different.(5)Study on the effects of mercury and cadmium stress on the synthesis of pharmacodynamic components and the expression of key enzyme genes of Atractylodes lancea and their correlation.This article choose EF-1α as internal genes,for key enzyme genes HMGR and FPPS of Atractylodes lancea under mercury and cadmium stresses to determine the quantity of the expression,the results showed that HMGR and FPPS in the leaves of Atractylodes lancea under mercury,cadmium stresses showed a trend of rise and fall of the first volume,which roots in the expression of key enzyme genes HMGR and FPPS weight was increased with the concentration of mercury,cadmium stress and a downward trend.In this paper,HPLC was used to determine the contents of three medicinal ingredients of Atractylodes lancea under mercury and cadmium stress.The results showed that the contents of β-eudesmol,atractylone and atractylodin decreased with the increase of mercury and cadmium stress.The correlation analysis of mercury and cadmium stress on the synthesis of pharmacodynamic components and key enzyme genes indicated that the expression levels of key enzyme genes HMGR and FPPS in rhizome of Atractylodes lancea showed significant positive correlation with the contents ofβ-eudesmol and atractylone.The grey correlation analysis indicated that HMGR and FPPS expression of key enzyme genes under mercury and cadmium stress contributed significantly to the contents of β-eudesmol,atractylone,which also proves that two key enzymes play a leading role in the regulation of β-eudesmol and atractylone synthesis.