2015 Fiscal Year Annual Research Report
Project/Area Number |
25820221
|
Research Institution | Saitama University |
Principal Investigator |
|
Project Period (FY) |
2013-04-01 – 2016-03-31
|
Keywords | Oxidative stress / Cesium / Antioxidant enzymes / Nitella pseudoflabellata / Charophyte |
Outline of Annual Research Achievements |
The effects of cesium (Cs) exposure on growth, metabolism and genetics have been reported for some terrestrial plants. However, there is little information regarding the impact of Cs exposure and Cs accumulation on aquatic flora, including charophytes.In this study, we used the charophyte, Nitella pseudoflabellata, as a model species to evaluate our hypothesis that Cs exposure would cause oxidative stress and negatively impact growth of the algae. We evaluated the impact of cesium (133 Cs) at four concentrations (0, 0.001, 0.01, and 0.1 mg/L) on growth, concentrations of chlorophyll and carotenoid pigments, and oxidative stress responses in the charophyte, Nitella pseudoflabellata, over 30 days. Oxidative stress was quantified by measuring anti-oxidant enzyme activities and H2O2 content. When compared with the control, significantly elevated activity levels of the anti-oxidative enzymes ascorbic peroxidase, catalase and guaiacol peroxidase were observed at 0.1 mg/L (all p<0.05), even though the H2O2 level was not significantly elevated. Carotenoid and chlorophyll a and b pigment levels were significantly reduced (all p<0.05) at Cs exposures of 0.01 and 0.1 mg/L. Photosynthetic efficiency (i.e. F v/F m) was significantly reduced (p<0.05) at Cs concentrations C0.001 mg/L. Significant reduction (p<0.05) of plant growth (i.e. shoot length) was also observed after 1 week of exposure at Cs concentrations C0.001 mg/L. Our results suggested that Cs exposure reduced plant growth and affected plant functioning via activating the defense mechanism against oxidative stress in Nitella.
|