镉胁迫对旱柳光合作用和内肽酶变化的影响

通过水培方法，添加不同浓度CdCl2(0、5、25、50 μmol·L^-1)处理14 d，测定叶绿素含量、核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)和磷酸烯醇式丙酮酸羧化酶(PEPC)活性、游离氨基酸含量及内肽酶活性，调查Cd对旱柳光合作用和内肽酶变化活性影响。结果发现：Cd处理降低了总叶绿素、叶绿素a、b含量； Rubisco活性随着介质中Cd浓度增加而降低；Cd抑制根和叶PEPC活性；同对照相比，根中游离氨基酸含量没有显著变化，而叶中游离氨基酸含量增加；不同浓度Cd处理降低根的内肽酶活性，高浓度Cd使叶内肽酶活力增加。这些结果表明，Cd通过降低叶绿素含量，促进叶内肽酶活性和抑制了CO₂羧化酶活性来影响旱柳光合作用。

Influences of Cadmium Stress on Photosynthesis and Endopeptidase Activities in Salix matsudana

Salix matsudana was grown in hydroponic culture for 14 d with CdCl₂ (0, 5, 25, 50 μmol·L^-1), the effects of Cd on photosynthetic performance and endopetidase activites of S. matsudana were investigated through analyzing chlorophyll, Rubisco, PEPC free amino acid and endopetidase. Total chlorophyll, chlorophyll a and b were decreased in Cd-treated plant, Rubisco activity was reduced with Cd levels in the medium, PEPC activity in roots and leaves showed an decline under Cd treatment，free amino acids in roots remained no significant change, but free amino acids in leaves were increased depending upon concentration of Cd; endopeptidase in roots was hindered at different dose of Cd, however, endopetidase in leaves increased at higher dose of Cd compared to control. The results showed that the effects of Cd on photosynthesis of S. matsudana were related to decrease in photosynthetic pigments, up-regulation of endopeptidase in leaves and inhibition of CO₂ carboxylation.