| This article study that two kinds of brake ferns Pteris multifida Poir. and Pteris vittata L. were raised in the different concentration trace element arsenic and lead environment stress.Utilize physiology and biochemical enzyme systems determination, the methods of the element content determined by ICP-MS law,as well as the cell structure observations of electron microscopy and so on ,Studying and comparing accumulation situation of the arsenic and lead element in these two kinds of brake ferns, at the same time exploring the changes of growth and development and physiology of Pteris vittata L.and Pteris multifida Poir. in the heavy metal stress.the study results showed:(1)With As-Pb exposure , the growth and development of Pteris multifida Poir. was suppressed in a certain degree, but can survive; the growth of Pteris vittata L is normal.Two months later, the ripe fronds have various degree toxicity symptoms to appear, and present positive correlation with media and time, the main symptom characteristics were that with the increased concentration and time the leaf edge and surface appear many reddish brown spots. Three months later, the poisoned position of Pteris multifida Poir appear programmed death. Observing the electric microscopy of ultrastructure of fronds of two ferns found cell structure appear irreversible destruction,and the heavy metal is deposited on cell wall and membrane。(2) Analyzing changes of physiological and biochemical in the heavy metal stress revealed that there are many kinds of anti-oxidant mechanism in Pteris multifida Poir. and Pteris vittata L.Including antioxidant enzyme system by composed of SOD and POD, soluble protein absorbing to heavy metal, the cycle of AsA-GSH-NADPH by composed of antioxidant GSH (glutathione) and AsA (Ascorbate).Heavy metal stress cause the SOD and POD activitives to rise, contents of soluble protein to drop, levels of GSH and AsA to increase.(3) By ICP-MS element determination ,it found Pteris multifida Poir and Pteris vittata L. did not have strong accuabilities to Pb, but the ablity to Pteris multifida Poir. and Pteris vittata L. .With As+Pb stress concentration with 900+1500mg/kg, Pb concentrations in roots, leaf stalks, fronds of Pteris vittata L. was 273.71±70.46, 182.81±120.48, 99.67±6. 86 mg/kg drywet respectively in the three months later,while with the same media, the capacity of Pb accumulated by Pteris multifida Poir. has 77.30±6 4.48, 32.91±4. 73, 20.10±0.75mg/kg drywet respectively. Pteris multifida Poir. and Pteris vittata L. have strong ability to accumulating As.The culture with 300+500mg/kg,As concentrations in the fronds of Pteris vittata L.reache1230.08±552.25mg/kg.When the culture concentration of As+Pb added to 900+1500mg/kg, it reach 3303.98±229.68mg/kgdrywet especially, and is far more than media with 900mg/kg; The accumulateing ability to As of Pteris multifida Poir was obviously lower than Pteris vittata L., when the culture concentration was 900 +1500mg/kg, As content of its fronds reach 1220.8±206.08mg/kgdrywet, which had fewer than the Pteris vittata L. with 300+500mg/kg media。(4) Heavy metal that As and Pb were accumulated in different organs of Pteris multifida Poir and Pteris vittata L..As mainly concentrated on being distributed in the fronds of Pteris multifida Poir and Pteris vittata L., the orders of arsenic concentrations in different parts of the two ferns were as follows:fronds >leaf stalks >roots,so As was easier to move to the ground parts of Pteris multifida Poir and Pteris vittata L.; Pb mainly accumulated in the roots of the plant, demonstrates roots >leafstalks>fronds,so Pteris multifida Poir. and Pteris vittata L. belong to root-hoarding plant .(5) The ion compartmentalization was a effective mechanism of the plant resisting toxicity of heavy metal. The result showed: Pb absorbed by Pteris vittata L. and Pteris multifida Poir mainly cumulated on the cell wall,and the cell wall prevented Pb from permeating in cells, and play certain protective roles on the normal metabolism of cells.The cell wall has function of depositing on As at the same time,In the high concentration of 900 +1500mg/kg,there are approximately more than 30% .As deposited the cell wall of Pteris vittata L.,and more than 40% were isolated by the cell wall in Pteris multifida Poir..The cytoplasmic supernatant of Pteris multifida Poir and Pteris vittata L accumulated the most mass As,the density accounts from 40% to 60% differently by cause of the culture medium.The capacity of accumulating the lead and arsenic of the organelle was far lower than the cell wall and cytoplasmic supernatant...
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