The Effect Of Endogenous Hormone Metabolism With Different Cadmium Concentrations In Sedumalfredii Hance

Hyperaccumulator Sedum alfredii has the ability of hyperaccumulation of cadmium,which has broad application prospects in phytoremediation.In our previous study,0.2 mg/L exogenous Abscisic acid(ABA)treatment can promote the absorption and extraction efficiency of Cd.However,there is not clear of the mechanism by exogenous ABA encourages the absorption of Cd.In this study,we used the Sedum alfredii Hance as material,analyze the effects of exogenous ABA on endogenous ABA and other endogenous hormones(auxin(IAA),gibberellin(GA3),and trans-zein(t-Z))of Sediam alfredii at different Cd treatments.To explore the relationship between Cd absorption and endogenous hormone content,endogenous hormone metabolism genes in Sedum alfredii.We interaction the perspective between exogenous ABA and endogenous hormone,analyze the possible mechanism of exogenous ABA promoting Cd absorption in Sedum alfredii,providing a theoretical basis for further improving the phytoremediation efficiency of Sedum alfredii.There is a result:1.The effect of ABA treatment on Cd absorption in Sedum alfredii.At low Cd treatment(75?M),0.2 mg/L ABA increased the Cd content in the root of Sedum alfredii with ABA treatment but decreased the Cd treatment in the shoot.ABA treatment increased the content of Cd in the shoot and root of Sedum alfredii under the condition of medium Cd(100?M).At high Cd treatment(150?M),ABA co-treatment significantly reduced the Cd content in shoot and root of Sedum alfredii.The result showed that ABA treatment at different concentrations of Cd had different on Cd absorption of Sedum alfredii,and 0.2 mg/L ABA treatment at 100?M Cd promoted the absorption and accumulation of Cd.2.Effect of ABA on the content of endogenous hormones(ABA,IAA,GA3 and t-Z)in Sedum alfredii.The contents of endogenous hormones in the root of Sedum alfredii changed significantly under the treatment of Cd and ABA co-treatment,while the contents of four endogenous hormones change little in the shoot.ABA treatment with low Cd(75 ?M)had little effect on four endogenous hormones in the shoot but significantly increased the contents of four endogenous hormones in the root of Sedum alfredii.Exogenous ABA increased the content of ABA in the shoot and four endogenous hormones in the root at 100 ?M Cd.ABA treatment with high Cd(150 ?M Cd)had little effect on the contents of four endogenous hormones in the shoot,but significantly reduced the contents of four endogenous hormones in Sedum alfrsdii.There was a significantly positive correlation between Cd content in root and four endogenous hormones.Under the condition of exogenous ABA,the IAA/ABA and GA/ABA ratios decreased with the increase of Cd treatment concentration,the balance of hormones was broken,the growth and development of Sedum alfredii were affected.ABA metabolic enzymes NCED and ABA8Hyd in Sedum alfredii affect endogenous ABA content by regulating the activity of metabolic enzymes,while ZEP and AAO genes are affected by post-transcriptional control and do not regulate the activity of corresponding enzymes.3.Effects of exogenous ABA on MDA content and expression of antioxidant enzyme-related genes in Sedum alfredii.Without ABA treatment,MDA content in the shoot and root increased with the increase of Cd treatment concentration.Under ABA treatment,MDA content in the shoot and root of Sedum alfredii decreased first and then improved with the increase of Cd treatment concentration.ABA treatment with 100 ?M Cd increased the expression of SOD,CAT and POD,enhanced the antioxidant enzyme activity,which may be an important reason for the low MDA content in the root and shoot of 100?M Cd.In conclusion,100 ?M Cd treatment with 0.2 mg/L ABA can increase Cd absorption in Sedum alfredii.Lower or higher Cd treatment with ABA inhibits the absorption.