Dynamic Monitoring And Study On The Mechanical Changes Of Rice Suspension Cells Under Arsenic Stress Using QCM

Soil heavy metals(HMs)impede plant growth initially reflecting as cell wall hardening and restricting of wall extensibility,namely HMs alter the mechanical properties of plant cell walls.In this thesis,Quartz crystal microbalance(QCM)and wide frequency QCM techniques were used to monitor the dynamic changes in viscoelasticity of rice suspension cells under the stresses of different concentrations of arsenic(As)toward the goal of establishing a new method to evaluate the effects of stresses of HMs on plants.The following is a summary of the main results.(1)Rice suspension cells were used as the test material,poly-L-lysine(PLL)films were created on the surfaces of QCM electrodes,the effectiveness of the PLL films to the adhesions of rice suspension cells was proved by electrochemical and QCM characterization techniques.(2)The viscoelastic characteristics of rice suspension cells under different osmosis pressures were studied.The results showed that under hypotonic conditions,the cells became harder with the decrease of osmotic pressure,while under hypertonic conditions,the cells initially became softer then became harder.(3)The viscoelastic properties of rice suspension cells under arsenic stress were studied.The results showed that under the stresses of arsenic with continuous concentration gradient,as the increase of arsenic concentration,the rice suspension cells became softer,but the softening rate of the cells slowed down,the cells became less sensitive;and the rate of softening was more rapid with As(III)than that of As(V),indicating that the toxicity As(III)is greater than that of As(V).Under the individual stress of either As(III)or As(V)of a constant concentrations,the rice suspension cells initially became softer and then became harder under the stress of low concentration of arsenic;and when the As(III)concentration reached 10 mM/L,the cells became damaged as indicated by the large fluctuations of cell's viscoelasticity and by changes in SOD activity,which further proved that the toxicity of As(III)is greater than that of As(V).(4)The effects of different concentrations of Arsenic stress on rice suspension cells under overtone 3(30 MHz)frequency were studied,and the results were corresponding tothose under the fundamental frequency of 10 MHz,which further proved the effect of arsenic stress on rice suspension cells.