Response Mechanisms Of Polysaccharide In Root Call Wall And Cadmium Adsorption Of Pakchoi With Different Cd-Tolerance

Pakchoi with stronger ability of cadmium accumulation in leaf vegetables,the cadmium concentration in shoots(eat)enters body through foods causing mischief.This experiment use high cadmium accumulating cultivar H and low cadmium accumulating cultivar L1?L2,seting different concentrations of cadmium,separating cell wall component and processing adsorption.Different concentrations of cadmium stress on growth and root cell wall polysaccharide components of total sugar,uronic acid and methyl pectin enzyme activity,different root cell wall varieties with different cadmium adsorption kinetics characteristics.The adsorption ability of Cd,provides a new idear to reveal the mechanism of Cd low accumulation varieties with low Cd accumulation,to provide technical support for it:1)Cadmium accumulation characteristics in different varieties:aboveground cadmium content,high cadmium accumulation varieties significantly higher than that of two varieties of low accumulation of L1 and L2;Root of cadmium content,high cadmium accumulation varieties significantly lower than the two lower accumulation of varieties L1,L2,there were no significant differences between two varieties of low accumulation.L2 and L1 transfer coefficient with smaller,the roots of the cumulative cadmium ion ability is stronger,which blocks the cadmium ions in the tissues and organs of the strong ability of transfer to the ground,so as to realize low cadmium accumulation of varieties of L1 and L2 aboveground(eat)low cadmium accumulation.2)The roots subcellular components allocation proportion of cadmium:cell wall is the cadmium accumulating primary site,with the increase of concentration of cadmium treatment,cadmium began to enter the cytoplasm,the cytoplasm cadmium accumulation rate increases,the proportion of organelles cadmium accumulation has been minimal.It was found that high accumulation of variety H contain higher proportions of cadmium in the cytoplasm,easy to its were shifted to the ground,causing the severe poisoning of rapeseed;Low cadmium accumulation of varieties of L1 and L2 cell accumulation ability is stronger,is significantly higher than high cadmium accumulation varieties H,is conducive to root block cadmium were shifted to the ground.3)The cell wall polysaccharide components differences:cadmium treatment,low cadmium accumulation L1 total sugar content increased most significantly,followed by low cadmium accumulation L2 varieties and varieties of high cumulative H total sugar content change is not obvious.The uronic acid content and total sugar content are similar,uronic acid plays a decisive role.Pectin uronic acid content in the cell walls are most,,hemicellulose 1 uronic acid content increased are most sharply,increase 2.1-4.9 times,show that in response to cadmium stress,the cell wall effect content are closely related with pectin uronic acid and hemicellulose 1 uronic acid.4)The methyl pectin enzyme activity:LI PME activity dramatically increases of cadmium treatment,showed a strong resistance to cadmium function;L2 PME activity also showed a rising trend and H PME activity did not change significantly.L1 with strong tolerance to cadmium closely related with its PME response mechanism.5)The perspective of the dynamics characteristics of the polysaccharide components of cadmium adsorption:the cell walls of different varieties of cadmium adsorption ability to comply with the following order:low accumulation of L1>L2>H.L2 pectin plays the biggest role in the cell walls of adsorption,LI hemicellulose 1 play an important role,and agree with the experiment "pectin content in the cell walls are most,and hemicellulose 1 increased most significantly",the results of show that cell wall polysaccharide components play an important role and its closely related to the content of pectin and hemicellulose 1.