The rate-limiting step for CO(2) assimilation at different temperatures is influenced by the leaf nitrogen content in
Wataru Yamori1, Takeshi Nagai, Amane Makino
1Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan. wataru.yamori@biochem.tohoku.ac.jp
Abstract:
Effects of nitrogen (N) supply on the limiting step of CO(2) assimilation rate (A) at 380 µmol mol(-1) CO(2) concentration (A(380) ) at several leaf temperatures were studied in several crops, since N nutrition alters N allocation between photosynthetic components. Contents of leaf N, ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) and cytochrome f (cyt f) increased with increasing N supply, but the cyt f/Rubisco ratio decreased. Large leaf N content was linked to a high stomatal (g(s) ) and mesophyll conductance (g(m) ), but resulted in a lower intercellular (C(i) ) and chloroplast CO(2) concentration (C(c) ) because the increase in g(s) and g(m) was insufficient to compensate for change in A(380) . The A-C(c) response was used to estimate the maximum rate of RuBP carboxylation (V(cmax) ) and chloroplast electron transport (J(max) ). The J(max) /V(cmax) ratio decreased with reductions in leaf N content, which was consistent with the results of the cyt f/Rubisco ratio. Analysis using the C(3) photosynthesis model indicated that A(380) tended to be limited by RuBP carboxylation in plants grown at low N concentration, whereas it was limited by RuBP regeneration in plants grown at high N concentration. We conclude that the limiting step of A(380) depends on leaf N content and is mainly determined by N partitioning between Rubisco and electron transport components.
More Related Videos
Related Concept Videos
The Calvin Benson Cycle
C4 Pathway and CAM
C4 Pathway
The C4 pathway is used by plants such as...
Inorganic Nitrogen Assimilation
Responses to Heat and Cold Stress
Carbon-dioxide Fixation
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...


