Abstract
Large variations in the enzymic properties of Rubisco exist among enzymes from different photosynthetic species. However, the CO2/O2 specificity (τ) from higher plants is the highest, and the difference in τ among higher plants is too small (only 5-6%) to give difference in photosynthesis. On the other hand, a variation in the specific activity is significant (30-40%), this difference reflects the difference in photosynthesis. Genetic analyses of Triticum genus suggest that higher specific activity of Rubisco is associated with the chloroplast-coded rbcL. However, since hybrid Rubisco with a foreign L-subunit does not function to its full potential, complete replacement of both L- and S-subunits is essential. Supplementation with an additional sense rbcS gene leads to an increase in Rubisco holoenzyme. However, since a negative correlation is found between Rubisco content and activation, it may be difficult to improve photosynthesis only by the enhancement of Rubisco content.
