Abstract
Rubisco is a rate-limiting factor for light-saturated photosynthesis under the present atmospheric CO2 pressures. Additionally, Rubisco is the most abundant leaf protein in C3 species. Therefore, Rubisco plays an important role in both photosynthesis and N economy in plant growth. However, Rubisco does not limit photosynthesis under elevated CO2 levels and the amount of Rubisco protein is clearly excessive under conditions of CO2 enrichment. We produced a series of transgenic rice plants with decreased Rubisco content by RNAi technology. OsRBCS3-1-1 and OsRBCS3-3-6, which have 70% wild type Rubisco, are obtained as the transformants with optimal Rubisco content for CO2-saturated photosynthesis. We investigated growth of these transformants under ambient conditions. Plant height, leaf age and tiller number were not significantly different between WT and transformants. The biomass of transformants was smaller than that of WT at 70d. This decrease in biomass in transformants was due to a significant decrease in RGR between d42 and 70.
