Was low CO(2) a driving force of C(4) evolution: Arabidopsis responses to long-term low CO(2) stress

The responses of long-term growth of plants under elevated CO(2) have been studied extensively. Comparatively, the responses of plants to subambient CO(2) concentrations have not been well studied. This study aims to investigate the responses of the model C(3) plant, Arabidopsis thaliana, to low CO(2) at the molecular level. Results showed that low CO(2) dramatically decreased biomass productivity, together with delayed flowering and increased stomatal density. Furthermore, alteration of thylakoid stacking in both bundle sheath and mesophyll cells, upregulation of PEPC and PEPC-K together with altered expression of a number of regulators known involved in photosynthesis development were observed. These responses to low CO(2) are discussed with regard to the fitness of C(3) plants under low CO(2). This work also briefly discusses the relevance of the data to C(4) photosynthesis evolution.