The Effects Of Cd On Malva Pusilla’s Physiology System And Root Cell Wall’s Immobilization

Malva pusilla is perennial herb of the Malva genus in the malvaceae family,Malva pusilla can be served as a soli’s Cadmium(Cd)remediation plant because it has extensive distribution,high fertility and high tolerance with Cd.In this study,Malva pusills was cultured in nutrient solution with different concentration of Cd.Testing the growth of Malva pusills with Cd,photosynthetic pigments content,anti-oxidization enzymes(SOD,POD,CAT)activity,content of malonaldehyde(MDA),content of osmotica(soluble glycans,soluble protein,proline)and absorbance elements provides the data to demonstrate the distribution of Cd in subcellular and changes in root cell wall,which supports Malva pusills can be used to repair Cd contaminate.The main findings are as follows:(1)The concentration of Cd affects the root length,stem diameter,plant height,fresh weight and photosynthetic pigments content,which the low Cd concentration enhance but high concentration inhibit.Plant roots reached highest growth when the concentration was 50μM,which increased 16.6%,but the growth was inhibited by200μM Cd.The growth of stem diameter was enhanced when the Cd concentration was between 50μM to 200μM,with the highest value at 100μM Cd.Plant height was inhibited when Cd concentration was 200μM,which decreased 10.46%.The affect was highest in root,and then leaf and stem,but when when Cd concentration was200μM,the total grand fish biomass decreased 36.71%.The changes of photosynthetic pigments content showed carotenoid > chlorophyll b > total chlorophyll content>chlorophyll a,reached highest value when Cd concentration was100μM.(2)The increasing of Cd coused cells damaging and the lipid membrane peroxidation.MDA in root and stem also increased compared with control groups,and at highest value when Cd was 100μM.MDA in stem deafferented with control group when Cd was between 50μM to 200μM,and the synthesis was inhibited at200μM.Leaf’s MDA was decreased with increasing Cd concnetraion.Cd activated the anti-oxidation system of Malva pusills,the anti-oxidation enzymes’(SOD、POD、CAT)activity increased by Cd,and decreased when Cd’s concentration above 100μM.Osmotic adjustment changed with Cd,proline in root,stem and leaf increased with Cd compared with control groups,to protect cell membrane.The changes of soluble glycans were same as photosynthetic pigments content,increasing as Cd’s concentration increased.Compared with control groups,soluble portions increased with concentration of Cd,but when the concentration higher than 100μM resulted in decreasing of soluble protein.(3)With different concentration,the absorbance of elements is different.The Cd increased the absorbance of Ca、Mg by stem,root and leaf;and its higher in stem and leaf.Cd decreased absorbance of Fe by root and stem and leaf.With Cd,the absorbance of Fe was inhibited in root and stem and leaf,and had significant decreased with control groups.The root and stem absorbance of Cu increased with Cd first,and decreased when Cd concentration was high,but absorbance was still higher than control group.For the Mn,the absorbance of root and stem and leaf was proportion with Cd’s concentration.There were no clear changes for the Zn absorbance with Cd.(4)Cd accumulated inside Malva pusills with increasing concentration,the accumulation was highest in root,and then stem and lowest in leaf.There are94.56%-96.94% Cd distribute in cell wall and soluble materials of root system’s subcellular.In Malva pusills the major binding points of Cd are pectin and hemicellulose I on root’s cell walls,which contributes 75.39%-80.77% Cd in cell wall.The distribution of uronic acid in polysaccharide content of and the total polysaccharide are same,increasing when Cd below 100μM and decreasing when Cd above 100μM.The kinetic study shows pectin is important binding position of Cd.