重金屬鎘及其與鋅組合對黃瓜毛狀根生長及其抗氧化酶活性的影響

為了探討利用黃瓜毛狀根來修復重金屬鎘 (Cd) 污染的可能性，研究了重金屬Cd單獨及其與鋅 (Zn) 組合對黃瓜毛狀根生長及其抗氧化酶SOD、POD活性變化的影響。結果表明，Cd≤10mg/L僅在培養5～15 d間促進黃瓜毛狀根生長，使根增粗;而Cd≥15mg/L則抑制黃瓜毛狀根生長，濃度愈高抑制作用愈明顯，側根變得短而細小。在供試的不同濃度Cd培養的黃瓜毛狀根中，除10mg/LCd外，其余Cd濃度培養的黃瓜毛狀根可溶性蛋白含量隨著培養時間的延長而逐漸下降；但其POD和SOD活性則隨著培養時間的延長而逐漸升高。與對照 (僅添加25mg/LZn) 相比，僅1mg/LCd+25mg/LZn組合在培養7～15 d期間促進黃瓜毛狀根生長；其余濃度Cd和25mg/LZn組合都抑制黃瓜毛狀根的生長，且Cd濃度愈高抑制作用越強，側根數目更少且短小，側根根尖變得腫脹；同時，除培養5 d外，25mg/LZn和不同濃度Cd組合培養的黃瓜毛狀根的生物量、POD和SOD活性均比單獨添加對應濃度Cd培養的毛狀根降低，但其可溶性蛋白含量則較之明顯提高。結果表明：黃瓜毛狀根具有較強的重金屬Cd耐受能力，高濃度Cd則抑制其生長；而鎘和鋅組合會隨著培養時間的延長而加重Cd對黃瓜毛狀根生長的抑制作用。
The effects of heavy metal cadmium(Cd),alone and in combination with zinc(Zn), on the root growth and activity of antioxidant enzymes superoxide dismutase(SOD) and peroxidase(POD) in Cucumis sativus L. hairy roots were studied. The purpose was to study the possibilities on using C.sativus hairy roots for phytoremediation of cadmium contamination. The results showed that less than 10 mg/L Cd enhanced the growth of C. sativus hairy roots and increased root diameter only in 5-15 days of root culture. At Cd concentrations above 15 mg/L hairy root growth was gradually inhibited with increasing Cd concentration. The roots formed were shorter with smaller lateral roots. Among all the Cd concentrations tested, except with 10 mg/L Cd, the soluble protein contents in the C. sativus hairy roots cultured with the other Cd concentrations decreased, but the POD and SOD activities increased gradually with time during the culture process. Further tests were conducted using a control culture containing 25 mg/L Zn alone. The addition of 1mg/L Cd to the 25 mg/L Zn culture stimulated the growth of C. sativus hairy roots after 7-15 days of growth, compared with the control. At all other Cd concentrations the growth of C. sativus hairy roots was inhibited compared to the control. Growth inhibition increased with increasing Cd concentration, and the hairy roots formed fewer, shorter and smaller lateral roots, the tips of which became swollen. After 5 days culture with different concentrations of Cd + 25 mg/L Zn, the root biomass and the activity of POD and SOD were lower than in C. sativus hairy roots cultured without the addition of Zn. However, the soluble protein content was significantly higher when the culture contained 25 mg/L Zn. Our results suggested that C. sativus hairy roots have higher tolerance to heavy metal Cd but higher concentration of Cd inhibited the growth. Cd in combination with Zn would result in more serious Cd-induced growth inhibition. Copyright © 2006 中國科學院微生物研究所《生物工程學報》.