鎘及其與鈣組合對褐脈少花龍葵毛狀根生長、抗氧化酶活性和吸收鎘的影響

為了探討利用褐脈少花龍葵毛狀根來修復重金屬鎘 (Cd) 污染的可能性，采用溶液培養法研究了Cd單獨及其與鈣 (Ca) 組合對褐脈少花龍葵毛狀根生長、抗氧化酶超氧化物歧化酶(SOD)和過氧化物酶 (POD) 活性及對Cd吸收的影響。結果表明，Cd≤50 μmol/L時能促進毛狀根生長，而高於100 μmol/LCd則抑制毛狀根生長，使其側根根尖變褐和變短，數目減少。與對照相比，不同濃度Cd培養的毛狀根可溶性蛋白含量和SOD活性先升高後逐漸下降；其丙二醛 (MDA) 含量顯著提高；100 μmol/LCd使毛狀根POD活性逐漸升高，但300 μmol/LCd則使毛狀根POD活性逐漸降低。與對照 (僅添加100 μmol/L或300 μmol/LCd的毛狀根) 相比，Cd和10～30 mmol/L CaCl₂組合培養使毛狀根可溶性蛋白含量和MDA含量降低；但提高其SOD活性；而100 μmol/L Cd和10～30 mmol/L CaCl₂結合培養的毛狀根POD活性均比對照低；而300 μmol/L Cd和10～30 mmol/L CaCl₂結合培養的毛狀根POD活性則均比對照提高。原子吸收分光光度法測定結果表明，毛狀根吸收和吸附的重金屬Cd含量隨著培養基中Cd濃度的升高而增加。但外源加入10～30 mmol/L CaCl₂能減少毛狀根對Cd的吸收，並調節其抗氧化酶SOD和POD活性，降低其膜脂過氧化水平而解除重金屬Cd對毛狀根生長的抑制或毒害。
To study if Solanum nigrum hairy roots can be used for phytoremediation of Cd contamination, we investigated the effects of cadmium (Cd) alone, and in combination with different concentrations of CaCl₂, on growth, activities of superoxide dismutase (SOD) and peroxidase (POD) and Cd absorption by hairy roots of S. nigrum L. var pauciflorum. The results showed that Cd concentrations of lower than 50 μmol/L enhanced the growth of hairy roots, while higher than 100 μmol/L inhibited growth and decreased the number of branched roots, also causing the root tips to become brown and shorter in length. In comparison with a control, the soluble protein content, the activities of SOD and POD in hairy roots cultures showed a trend of first increased and then gradually decreased, while the malondialdehyde (MDA) content significantly increased, when increasing the Cd concentrations. Cd concentration of 100 μmol/L or 300 μmol/L in combination with 10–30 mmol/L CaCl₂ resulted in a decreased content of soluble protein and MDA in the hairy roots, but an enhanced SOD activity. The increased POD activities were observed when cultured in 100 μmol/L Cd and 10–30 mmol/L CaCl₂ but decreased when cultured in 300 μmol/L Cd and 10–30 mmol/L CaCl₂. Atomic Absorption Spectrometry determination showed that the Cd absorbed and by the hairy roots increased along with the increase of Cd concentration. The exogenous addition of 10–30 mmol/L CaCl₂ could reduce the toxicity of Cd. This was achieved on one hand by reducing the absorption of Cd, on the other hand by decreasing the lipid peroxidation through regulating the activities of antioxidant enzymes SOD and POD in the hairy roots. Copyright © 2010 中國科學院微生物研究所《生物工程學報》.