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(W/MF171a) Assessment of ozone pollution impact on plants using oxidative modifications of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Biolley, J.P.1, Kanoun, M.1, Bazsères, A.2, Goulas, P.1, 1 2 ABSTRACT- Tropospheric pollution by ozone results in a decline in carbon gain attributed to reduced carboxylation activity of Rubisco or/and to a decrease in its quantity. Using open-top chambers technology, bean plants (Phaseolus vulgaris) were submitted to 12, 70, 89 or 109 ppb ozone from 10:00 to 17:00 hours. After an exposure of 21 d, primary leaves of six plants per treatment were sampled. To assess the direct impact of ozone on Rubisco small subunit (SSU) we measured the formation of aldehydes and ketones in amino acids residues. After derivatization of carbonyl groups with 2,4-dinitrophenylhydrazine (DNPH), we developed a sandwich type ELISA technique to fix specifically SSU (with anti-SSU antibodies) and to quantify the oxidised sites it contained with anti-DNP antibodies conjugated with alkaline phosphatase. The mean number of carbonyl groups, expressed as arbitrary absorbance unit, increased with ozone concentration: 0.09a, 0.6b, 0.9c and 1.1c (different letters mean statistically different) for 12, 70, 89 and 109 ppb ozone, respectively. Furthermore, these oxidative modifications were associated with a decrease in the amount of SSU that was about three fold inferior in leaves from the three higher polluted atmospheres as compared to the control. So, Rubisco appears sensitive enough to become a helpful biomarker for assessing plant damage caused by an oxidising gaseous pollutant. Key words: Biomarker, ozone, oxidation, Rubisco |
