Increase In CO₂ Permeability (Diffusion Conductance) In Leaves Of Transgenic Rice Plant Over-expressing Barley Aquaporin

Abstract

Aquaporins are membrane proteins forming water channels. Human aquaporin AQP1 is permeable for gas CO₂ in addition to H₂O. In Characean cells and Vicea leaflets, physiological experiments indicated the correlation between water permeability and CO₂ permeability in the plasma membrane. In the present study, we measured the CO₂ permeability (diffusion conductance, g_i) in leaves of transgenic rice plants over-expressing barley aquaporin (HvPIP2;1). Expressions of introduced gene and deduced protein were confirmed with Southern, Northern, and Western analysis in T₀ plants, and descendent T₂ leaves were subjected to g_i measurement. Transgenic plants showed almost identical assimilation with non-transgenic control, but 20% increase in g_i was found in transgenic leaves. Higher g_i was observed in higher HvPIP2;1-expressing individuals.