Abstract
In higher plants, the balance between carbon and nitrogen must be tightly coordinated. However, details still are unclear. To clarify the effect of alteration of photosynthetic capacity on nitrogen metabolism, we generated and evaluated the photosynthesis-elevated Arabidopsis (ApFS) expressing FBP/SBPase in chloroplasts. In ApFS, the photosynthetic activity and the total fresh weight were 1.3- and 1.2-fold higher, respectively, than those of wild type. In 2-week-old plants, the contents of photosynthate in ApFS were higher than those in wild type, whereas the contents of various amino acids were lower. Expression levels of the genes involved carbon and nitrogen metabolisms were not altered. In 5-week-old plants, the expressions of genes involved in the Calvin cycle were reduced, whereas the nitrogen metabolisms-related genes were induced in ApFS. These results suggest that the change of metabolites at early growth stage causes the temporary imbalance of C/N ratio followed by the regulation of the gene expression involved in the Calvin cycle and nitrogen metabolism due to maintenance of C/N balance in ApFS.
