Physiological And Molecular Response Of Chrysanthemum Indicum To Heavy Metal Cadmium

Chrysanthemum indicum is a perennial herb,it has the characteristics of large biomass,strong adapt ability and extensive management.It is a wild plant resource with excellent characteristics and has great garden application value.At present,the related research of C.indicum is mainly in the aspects of introduction and cultivation,pharmacology,chemical composition and gene expression,and there is less research on its heavy metal screening and resistance.Therefore,this experiment will introduce C.indicum in the nursery of the Northeast Forestry University,add an exogenous heavy metal cadmium(Cd)solution under hydroponic conditions,screen it for Cd tolerance,and then select 2 strains from the three types of Cd tolerant C.indicum with low,medium and high Cd to explore the effects of Cd treatment on different C.indicum strains the influence of physiological characteristics and changes in molecular response.The main findings are as follows:1.Cd treatment had different effects on morphological indexes and chlorophyll fluorescence indexes of C.indicum strains.After principal component analysis of plant height,stem diameter,leaf length,leaf width,dry weight,F0/Fm,Fv,/Fm,NPQ and qP,the cumulative contribution rate of the first four principal components was 80.32%,which was enough to represent most of the information of the nine indexes determined by the tested materials.Through the calculation of membership function value,the comprehensive measurement value of Cd tolerance was obtained and cluster analysis was carried out.It was divided into three grades:low Cd tolerance,medium Cd tolerance and high Cd tolerance.2.After Cd treatment,the Cd content in shoot was less than that in root,which had the characteristics of enrichment plants.Cd enrichment was mainly located in the root.The MDA content in high Cd tolerant strains was lower than that in low Cd tolerant strains.The activities of POD and CAT in the six strains were significantly higher than those in the control group,and the activities of SOD,POD and CAT in the strains with high Cd tolerance were higher than those in the strains with medium and low Cd tolerance.3.The Gs,Pn and Tr of the six C.indicum strains after Cd treatment were significantly lower than those of the control group,and the Ci value was significantly increased.The Gs,Pn and Tr values of high Cd tolerance strains were higher than those of medium and low Cd tolerance strains,and the Ci value of high Cd tolerance strains was far lower than that of medium and low Cd tolerance strains.After Cd treatment,the chlorophyll a content,chlorophyll b content and total chlorophyll content of medium and high Cd tolerance strains were higher than those of low Cd tolerance strains.4.CiPCS1 gene was up-regulated after Cd treatment,and the relative expression of CiPCS1 gene in roots and leaves of high Cd tolerance strains was significantly higher than that of low Cd tolerance strains.CiPCS1 gene had the same expression pattern in roots and leaves of high Cd tolerance strains.The expression abundance of CiCAX1 gene in roots and leaves of high Cd tolerance strains was much higher than that in low Cd tolerance strains,and the expression pattern of CiCAX1 gene in roots and leaves of high Cd tolerance strains was the same.The expression level of CiCAX3 gene in roots,stems and leaves of Cd tolerant strains was much higher than that of Cd tolerant strains.CiCAX3 gene had the same expression pattern in roots and stems of Cd tolerant strains.The overall expression levels of CiCAX2,CiCAX4 and CiCAX5 genes were low.CiHMA2 and CiHMA3 genes were mainly highly expressed in roots and leaves after Cd treatment.The upregulation of CiHMA2 gene in high Cd tolerant strains in roots and leaves was higher than that in low Cd tolerant strains,and the high Cd tolerant strains in roots and leaves had the same expression pattern.The expression level of CiHMA3 gene in high Cd tolerant strains in roots and leaves was higher than that in medium and low Cd tolerant strains.There was the same expression pattern between high Cd tolerant strains in leaves,and the same expression pattern between low Cd tolerant strains in roots.The overall expression level of CiHMA1 gene in C.indicum was low.