Abstract
The effect of constitutive and dark-induced expression of Solanum tuberosum phosphoenolpyruvate carboxylase (PEPC) on the opening state of stomata and photosynthetic performance in Arabidopsis thaliana plants was studied. Transcript accumulation analyses of the A. thaliana dark-induced (Din10 and Din6) and the Pisum sativum asparagine synthetase 2 promoters (Asn2) in transiently transformed tobacco leaves showed that Din10 promoter induced more DsRed accumulation in the dark compared to the other din genes. Overexpression of PEPC under the control of the constitutive enhanced CaMV 35S (p35SS) and dark-induced Din10 promoter in stably transformed A. thaliana plants increased the number of opened stomata in dark adapted leaves. Gas exchange measurements using A. thaliana plants transgenic for p35SS-PEPC and Din10-PEPC revealed a marked increase in stomatal conductance, transpiration, and dark respiration rates measured in the dark compared to wild-type plants. Moreover, measurement of CO(2) assimilation rates at different external CO(2) concentrations (C(a) ) and different light intensities shows an increase in the CO(2) assimilation rates in transgenic Arabidopsis lines compared to wild-type plants. This is considered as first step towards transferring the aspects of Crassulacean acid metabolism-like photosynthetic mechanism into C3 plants.