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Effects of chronic ozone and elevated atmospheric CO 2 concentrations on ribulose‐1,5‐bisphosphate in soybean ( Glycine max )
Author(s) -
Reid Chantal D.,
Fiscus Edwin L.,
Burkey Kent O.
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.1399-3054.1999.106404.x
Subject(s) - rubisco , ribulose , photosynthesis , ozone , ribulose 1,5 bisphosphate , photorespiration , chemistry , glycine , carbon dioxide , oxygenase , pyruvate carboxylase , botany , horticulture , biochemistry , biology , enzyme , amino acid , organic chemistry
Ribulose‐1,5‐bisphosphate (RuBP) pool size was determined at regular intervals during the growing season to understand the effects of tropospheric ozone concentrations, elevated atmospheric carbon dioxide concentrations and their interactions on the photosynthetic limitation by RuBP regeneration. Soybean ( Glycine max [L.] Merr. cv. Essex) was grown from seed to maturity in open‐top field chambers in charcoal‐filtered air (CF) either without (22 nmol O 3 mol −1 ) or with added O 3 (83 nmol mol −1 ) at ambient (AA, 369 μmol CO 2 mol −1 ) or elevated CO 2 (710 μmol mol −1 ). The RuBP pool size generally declined with plant age in all treatments when expressed on a unit leaf area and in all treatments but CF‐AA when expressed per unit ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) binding site. Although O 3 in ambient CO 2 generally reduced the RuBP pool per unit leaf area, it did not change the RuBP pool per unit Rubisco binding site. Elevated CO 2 , in CF or O 3 ‐fumigated air, generally had no significant effect on RuBP pool size, thus mitigating the negative O 3 effect. The RuBP pools were below 2 mol mol −1 binding site in all treatments for most of the season, indicating limiting RuBP regeneration capacity. These low RuBP pools resulted in increased RuBP regeneration via faster RuBP turnover, but only in CF air and during vegetative and flowering stages at elevated CO 2 . Also, the low RuBP pool sizes did not always reflect RuBP consumption rates or the RuBP regeneration limitation relative to potential carboxylation (%RuBP). Rather, %RuBP increased linearly with decrease in the RuBP pool turnover time. These data suggest that amelioration of damage from O 3 by elevated atmospheric CO 2 to the RuBP regeneration may be in response to changes in the Rubisco carboxylation.