中文摘要：

本实验通过对沉水植物水车前（offelia alismoides）和黑藻（Hydrilla verticillata）进行低浓度C02诱导，研究其光合特性的变化。研究显示，诱导后，水车前的PEPC／Rubisco活性比值由0．45上升到4．17，黑藻由0．47上升到4．17，两种植物的C4途径光合酶PEPC和NAD—ME的活性升高了10倍左右，其他C4光合酶如NAD—MDH和PPDK的活性也大幅升高；诱导后，水车前和黑藻的其他光合特性也发生了显著变化：净光合速率比对照分别提高了50．8％和74．1％，O2对处理组光合速率的抑制分别为对照组的35％和60％，叶绿素荧光基本参数也有显著性变化。研究结果表明，经低浓度C02诱导，水车前和黑藻光合碳同化途径可能由C3转变成为C4。

英文摘要：

Photosynthetic characteristics of Ottelia alismoides and Hydrilla verticillata were studied after the two species were incubated under low CO2 conditions. The PEPC/Rubisco ratio of O. alismoides increased from 0.45 to 4. 17 and of H. verticillata increased from 0.47 to 4. 17 after low CO2 induction. The activity of PEPC and NAD-ME increased more than 10-fold and other C4 enzymes such as NAD-MDH and PPDK also increased significantly after low CO2 induction. Other photosynthetic characteristics also changed significantly. The net photosynthetic rate of O. alismoides and H. verticillata increased by 50. 8% and 74. 1%, respectively, and the oxygen inhibition on photosynthetic rate of the two species decreased to 35% and 60%, respectively, after low CO2 induction. The chlorophyll fluorescence parameters also changed after low CO2 induction. All these facts indicated that photosynthetic carbon assimilation of O. alismoides and H. verticillata might shift from C3 to C4 after low CO2 induction.