Effects of OsRCA Overexpression on Rubisco Activation State and Photosynthesis in Maize

Ribulose–1,5–bisphosphate carboxylase/oxygenase (Rubisco) is the rate–limiting enzyme for photosynthesis. Rubisco activase (RCA) can regulate the Rubisco activation state, influencing Rubisco activity and photosynthetic rate. We obtained transgenic maize plants that overproduced rice RCA (OsRCA(OE)) and evaluated photosynthesis in these plants by measuring gas exchange, energy conversion efficiencies in photosystem (PS) I and PSII, and Rubisco activity and activation state. The OsRCA(OE) lines showed significantly higher initial Rubisco activity and activation state, net photosynthetic rate, and PSII photochemical quantum yield than wild–type plants. These results suggest that OsRCA overexpression can promote maize photosynthesis by increasing the Rubisco activation state.