Polyamine metabolism and physiological responses of Potamogeton crispus leaves under lead stress

Aquatic macrophytes were found to be the potential scavengers of heavy metals from aquatic environment. In this study, influences of ladder concentration of lead (Pb) on the leaves of Potamogeton crispus Linn were studied after 7 days of treatment. The accumulation of Pb, nutrient element contents, the generation rate of superoxide radical (O ₂ ·⁻ ), MDA, proline, and polyamine (PAs) contents, as well as the activities of diamine oxidases (DAO), polyamine oxidases (PAO), arginine decarboxylase (ADC), and ornithine decarboxylase (ODC) in P. crispus leaves were investigated. The result indicated that Pb treatment decreased the activity of DAO, whereas the proline content, MDA content, the generation rate of O ₂ ·⁻ and the activity of ODC increased in different degrees. Meantime, Pb treatment significantly increased the free putrescine (Put) level and made other PAs levels dynamic changes. The activities of PAO and ADC were declined firstly and then enhanced with the increase in the Pb concentration.