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Carbon fixation in Pinus halepensis submitted to ozone. Opposite response of ribulose‐1,5‐bisphosphate carboxylase/oxygenase and phospho enol pyruvate carboxylase
Author(s) -
Fontaine V.,
Pelloux J.,
Podor M.,
Afif D.,
Gérant D.,
Grieu P.,
Dizengremel P.
Publication year - 1999
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1999.105201.x
Subject(s) - rubisco , ribulose 1,5 bisphosphate , phosphoenolpyruvate carboxylase , pyruvate carboxylase , carbon fixation , oxygenase , photosynthesis , ozone , chemistry , ribulose , biochemistry , botany , biology , enzyme , organic chemistry
The effects of ozone exposure on carbon‐fixation‐related processes in Pinus halepensis Mill. needles were assessed over 3 months under controlled conditions. Ozone fumigation (200 ppb) did not induce a modification of either net CO 2 assimilation or stomatal conductance in 1‐year‐old needles, whereas ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activity was shown to be reduced by a half. Moreover, this ozone‐induced reduction in Rubisco activity was associated with a decrease in the quantity of Rubisco, as determined by the decrease in the large subunit (LSU). On the other hand, 200‐ppb ozone fumigation induced a strong increase in both activity and quantity of another carboxylating enzyme, phospho enol pyruvate carboxylase (PEPC, EC 4.1.1.31), generally considered in C 3 plants to participate in carbon catabolism processes. Ozone induced a significant decrease in the Rubisco/PEPC activity ratio which promotes the role of PEPC in trees under ozone stress. The role of this carboxylase will be discussed.