Effect Of Silicon On Enzymatic Activities And Proteome Of Populus Euramericana Clone I-214 Under Cadmium Stress

Silicon(Si),the second abundant element in the crust followed by oxygen,is a beneficial element for plant growth.Silicon can regulate the resistance of plants to biotic and abiotic stresses has been extensively reported.Populus euramericana clone I-214 is one of the widely cultivated populus varieties,and has showed great potential in phytoremediation of Cadmium(Cd)-contaminated soils.In this study,the hydroponic method by Hoagland nutrient solution was used to investigate the growth,physiology,enzyme activities and proteome to study the mitigating effect of Si on Cd stress in clone I-214.The main results are as follows:(1)Si significantly increased the fresh and dry weight of shoot of clone I-214 under cadmium stress,but not significantly influenced the dry weight of root,and the fresh weight of root reduced slightly.Si significantly reduced the ratio of root to shoot.Si significantly reduced the cadmium accumulation in roots and leaves,but increased the accumulation of cadmium in the stem.(2)Si increased the content of chlorophyll b in leaves of clone I-214 under cadmium stress.Si significantly increased the content of soluble sugar in leaves of clone I-214 under cadmium stress.(3)Si significantly increased the activity of SOD in clone I-214 under cadmium stress,but reduced the activity of POD and CAT.Si significantly reduced the high activity of PPO caused by cadmium stress.Si effectively reduced the high activity of AAO and GR caused by cadmium stress.(4)According to the proteomics identification,a total of 452 differentially expressed proteins(257 up-regulated proteins and 195 down-regulated proteins)were identified under cadmium stress,and total of 714 differentially expressed proteins(401 up-regulated proteins and 313 down-regulated proteins)were identified under Si+Cd treatment.A total of 126 differentially expressed proteins were co-expressed in the Si+Cd treatment,and their main functions are as follows:protein binding,organic cyclic compound binding,nucleoside phosphate binding,hydrolase activity,catalytic activity,structural constituent of ribosome,ATP Binding,enzyme regulator activity,transporter activity and so on.