Subambient growth CO2 leads to increased Rubisco small subunit gene expression in developing rice leaves

To test the hypothesis whether low atmospheric [CO2] can cause an increase of Rubisco small subunit gene expression, rice (Oryza sativa L.) growing under ambient [CO2] at 350μmol mol−1 was switched to subambient [CO2] at 175μmol mol−1 during late vegetative stage. After the switch, photosynthesis rate of developing leaves initially declined but partially recovered after 8 days. Transcript levels of the Rubisco small subunit gene (rbcS) in developing leaves increased within three days to almost twice that of ambient-CO2 controls, followed later by an up-regulation of Rubisco total activity and protein content.