Abstract
Chloroplastic 2-oxoglutarate/malate transporter (OMT) mediates between carbon and nitrogen metabolic pathways in concert with dicarboxylate transporter, and also constitutes malate valve together with NADP-malate dehydrogenase (MDH) isozymes. We produced Arabidopsis transformants overexpressing the OMT and NADP-MDH, and examined whether the tolerance to environmental stresses or ability of nitrate assimilation is improved in the transformants. The rate of oxaloacetate-dependent malate synthesis/efflux was higher in chloroplasts from the OMT/MDH double overexpressed plants compared with WT chloroplasts, and, therefore, we concluded that the capability of malate valve was improved in the transformants. Although growth rate of the transformants was similar with that of WT, the contents of some organic and amino acids were increased in the transformant's leaves. Additionally, a decrease in foliar Fv/Fm value in response to high light illumination was reduced in the transformants. Therefore, it is thought that the ability to avoid photoinhibition in response to environmental stresses is improved in the transformants.
