Phosphatidic acids (PAs) are a key intermediate in phospholipid biosynthesis, and a central element in numerous signalling pathways. Functions of PAs are related to their fundamental role in molecular interactions within cell membranes modifying membrane bending, budding, fission and fusion. Here we tested the hypothesis that PAs are capable of direct transport of ions across bio-membranes. We have demonstrated that PAs added to the maize plasma membrane vesicles induced ionophore-like transmembrane transport of Ca2+, H+ and Mg2+. PA-induced Ca2+ fluxes increased with an increasing PAs acyl chain unsaturation. For all the PAs analysed, the effect on Ca2+ permeability increased with increasing pH (pH 8.0>pH 7.2>pH 6.0). The PA-induced Ca2+, Mg2+ and H+ permeability was also more pronounced in the endomembrane vesicles as compared with the plasma membrane vesicles. Addition of PA to protoplasts from Arabidopsis thaliana (L.) Heynh. roots constitutively expressing aequorin triggered elevation of the cytosolic Ca2+ activity, indicating that the observed PA-dependent Ca2+ transport occurs in intact plants.

Department of Plant Cell Biology and Bioengineering Biological Faculty Belarusian State University 4 Independence Avenue Minsk 220030 Belarus

Department of Plant Cell Biology and Bioengineering Biological Faculty Belarusian State University 4 Independence Avenue Minsk 220030 Belarus; and Corresponding authors Emails

Department of Plant Physiology and Biochemistry St Petersburg State University Universitetskaya em 7 9 199034 St Petersburg Russia

Department of Plant Physiology and Biochemistry St Petersburg State University Universitetskaya em 7 9 199034 St Petersburg Russia; and Corresponding authors Emails

Institute of Experimental Botany AS CR vvi Rozvojová 263 165 02 Prague 6 Lysolaje Czech Republic

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