Accumulation,subcellular distribution,and chemical forms of copper in Myriophyllum spicatum L.
To explore the accumulation and tolerance mechanism in Myriophyllum spicatum L.,a hydroponic experiment was conducted to investigate its growth,physiological response,and copper uptake translocation.The subcellular distribution and chemical form of copper in roots,stems,and leave were further analyzed.M.spicatum could survive under different copper treatments.However,when the copper concentration exceeded 50 mg·L-1,the biomass of roots,stems,and leave of M.spicatum decreased by 53.48%,36.99%,and 32.22%,respectively,compared to that under the control treatment(copper 0 mg·L-1).Following copper treatment,the copper contents in the roots,stems,and leave of M.spicatum were 11.81-186.34 mg·kg-1,1.32-7.89 mg·kg-1,and 2.11-11.99 mg·kg-1,respectively,with higher contents in the roots than in the shoots.The subcellular distribution of copper in M.spicatum was mainly located in the cell wall parts of the roots,stems,and leave(36.49%-49.61%,45.44%-49.92%,and 41.45%-55.92%,respectively),followed by the soluble component(21.65%-25.99%,23.03%-27.65%,and 18.01%-34.63%,respectively).The copper existed in HCl-,HAc-,and ethanol-extracted forms in M.spicatum,accounting for 76.34%to 86.67%,all with low activity.These results show that M.spicatum has good copper accumulation,and its root tolerance is greater than that of stems and leaves.The primary resistance mechanism underlying copper accumulation and tolerance in M.spicatum might involve the presence of copper in the cell wall or soluble components(vacuoles)in an adsorbed state or a low-active form,such as protein or pectate.
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