The plasma membrane (PM) H+-ATPase has been proposed to play important transport and regulatory rules in plant physiology, including its participation in auxin-induced acidification in coleoptile segments. This enzyme is encoded by a family of genes differing in tissue distribution, regulation, and expression level. A major expressed isoform of the maize PM H+-ATPase (MHA2) has been characterized. RNA gel blot analysis indicated that MHA2 is expressed in all maize organs, with highest levels being in the roots. In situ hybridization of sections from maize seedlings indicated enriched expression of MHA2 in stomatal guard cells, phloem cells, and root epidermal cells. MHA2 mRNA was induced threefold when nonvascular parts of the coleoptile segments were treated with auxin. This induction correlates with auxin-triggered proton extrusion by the same part of the segments. The PM H+-ATPase in the vascular bundles does not contribute significantly to auxin-induced acidification, is not regulated by auxin, and masks the auxin effect in extracts of whole coleoptile segments. We conclude that auxin- induced acidification in coleoptile segments most often occurs in the nonvascular tissue and is mediated, at least in part, by increased levels of MHA2.8915331544Altabella, T., Palazón, J., Ibarz, E., Piñol, M.T., Serrano, R., Effect of auxin concentration and growth phase on the plasma membrane H+-ATPase of tobacco calli (1990) Plant Sci., 70, pp. 209-214Ballas, N., Wong, L.-M., Ke, M., Theologis, A., Two auxinresponsive domains interact positively to induce expression of the early indoleacetic acid-inducible gene PS-IAA4/5 (1995) Proc. Natl. Acad Sci. USA, 92, pp. 3483-3487Bouché-Pillon, S., Fleurat-Lessard, P., Fromont, J.C., Serrano, R., Bonnemain, J.L., Immunolocalization of the plasma membrane H+-ATPase in minor veins of Vicia faba in relation to phloem loading (1994) Plant Physiol., 105, pp. 691-697Boutry, M., Michelet, B., Goffeau, A., Molecular cloning of a family of plant genes encoding a protein homologous to plasma membrane H+-translocating ATPases (1939) Biochem. Biophys Res. Commun, 162, pp. 567-574Bewles, D.J., The wound response of plants (1991) Curr. Biol., 1, pp. 165-167Briskin, D.P., The plasma membrane H+-ATPase of higher plant cells. Biochemistry and transport function (1990) Biochim. Biophys. Acta, 1019, pp. 95-109Cho, H.T., Hong, Y.N., Effect of IAA on synthesis and activity of the plasma-membrane H+-ATPase of sunflower hypocotyls, in relation to IAA-induced cell elongation and H+ secretion (1995) J. Plant Physiol, 145, pp. 717-725Church, G.M., Gilbert, W., Genomic sequencing (1984) Proc. Natl. Acad. Sci. USA, 81, pp. 1991-1995Coen, E.S., Romero, J.M., Doyle, S., Elliot, R., Murphy, G., Carpenter, R., Floricaula: A homeotic gene required for flower development in Antirrhinum majus (1990) Cell, 63, pp. 1311-1322Dewitt, N.D., Harper, J.F., Sussman, M.R., Evidence for a plasma membrane proton pump in phloem cells of higher plants (1991) Plant J., 1, pp. 121-128Evans, M.L., The action of auxin on plant cell elongation (1985) Crit. Rev. Plant Sci., 2, pp. 317-365Ewing, N.N., Bennett, A.B., Assessment of the number and expression of P-type H+-ATPase genes in tomato (1994) Plant Physiol, 106, pp. 547-557Ewing, N.N., Wimmers, L.E., Meyer, D.J., Chetelat, R.T., Bennett, A.B., Molecular cloning of tomato plasma membrane proton-ATPase (1990) Plant Physiol., 94, pp. 1874-1881Feinberg, A.P., Vogelstein, B., A technique for radiotabeling DNA restriction endonuclease fragments to high specific activity (1983) Anal. Biochem., 132, pp. 6-13Franco, A.R., Gee, M.A., Guilfoyle, T.J., Induction and superinduction of auxin-responsive mRNAs with auxin and protein synthesis inhibitors (1990) J. Biol. Chem., 265, pp. 15845-15849Fry, S.C., Smith, R.C., Renwick, K.F., Martin, D.J., Hodge, S.K., Matthews, K.J., Xyloglucan endotransglycosylase, a new wall-loosening enzyme activity from plants (1992) Biochem. J., 282, pp. 821-828Fukuhara, T., Pak, J.-Y., Ohwaki, Y., Tsujimura, H., Nitta, T., Tissue-specific expression of the gene for a putative plasma membrane H+-ATPase in a seagrass (1996) Plant Physiol., 110, pp. 35-42Gabathuler, R., Cleland, R.E., Auxin regulation of a proton translocating ATPase in pea root plasma membrane vesicles (1985) Plant Physiol, 79, pp. 1080-1085Hager, A., Avena coleoptile segments Hyperelongation growth after anaerobic treatment (1980) Z. Naturforsch, 35 C, pp. 794-804Hager, A., Moser, I., Acetic acid esters and permeable weak acids induce active proton extrusion and extension growth of coleoptile segments by lowering the cytoplasmic pH (1985) Planta, 163, pp. 391-400Hager, A., Menzel, H., Krauss, A., Versuche und Hypothese zur Primärwirkung des Auxins beim Streckungwachstum (1971) Planta, 100, pp. 47-75Hager, A., Debus, G., Edel, H.-G., Stransky, H., Serrano, R., Auxin induces exocytosis and the rapid synthesis of a high-turnover pool of plasma membrane H+-ATPase (1991) Planta, 185, pp. 527-537Hara, Y., Urayama, O., Kawakami, K., Nojima, H., Nagamune, H., Kojima, T., Ohta, T., Nakao, H., Primary structures of two types of α-subunit of rat brain Na+/K+-ATPase deduced from cDNA sequences (1987) J. Biochem., 102, pp. 43-58Haro, R., Garciadeblas, Rodriguez-Navarro, A., A novel P-type ATPase from yeast involved in sodium transport (1991) FEBS Lett., 291, pp. 189-191Harper, J.F., Surowy, T.K., Sussman, M.R., Molecular cloning and sequence of a cDNA encoding the plasma membrane proton pump (H+-ATPase) of Arabidopsis thaliana (1989) Proc Natl. Acad. Sci. USA, 86, pp. 1234-1238Harper, J.F., Manney, L., Dewitt, N.D., Yoo, M.H., Sussman, M.R., The Arabidopsis thaliana plasma membrane H+-ATPase multigene family (1990) J. Biol. Chem., 265, pp. 13601-13608Houlné, G., Boutry, M., Identification of an Arabidopsis thaliana gene encoding a plasma membrane H+-ATPase whose expression is restricted to anther tissues (1994) Plant J., 5, pp. 311-317Jackson, D., Culiañez-Maciá, F., Prescott, A.G., Roberts, K., Martin, C., Expression patterns of myb genes from Antirrhinum flowers (1991) Plant Cell, 3, pp. 115-125Jin, Y.-K., Bennetzen, J.L., Integration and nonrandom mutation of a plasma membrane proton ATPase gene fragment within the Bs1 retroelement of maize (1994) Plant Cell, 6, pp. 1177-1186Johansson, F., Sommarin, M., Larsson, C., Fusicoccin activates the plasma membrane H+-ATPase by a mechanism involving the C-terminal inhibitory domain (1993) Plant Cell, 5, pp. 321-327Kempter, B., Luppa, P., Neumeier, D., A short procedure for Southern blotting on neutral and anionic membranes (1991) Trends Genet., 7, pp. 109-110Kroczek, R.A., Siebert, E., Optimization of Northern analysis by vacuum-blotting, RNA-transfer visualization and ultraviolet fixation (1990) Anal. Biochem, 184, pp. 90-95Li, Y., Liu, Z.-B., Shi, X., Hagen, G., Guilfoyle, T.J., An auxin-inducible element in soybean SAUR promoters (1994) Plant Physiol., 106, pp. 37-43Liu, Z.-B., Ulmasov, T., Shi, X., Hagen, G., Guilfoyle, T.J., Soybean GH3 promoter contains multiple auxin-inducible elements (1994) Plant Cell, 6, pp. 645-657Logemann, J., Schell, J., Willmitzer, L., Improved method for the isolation of RNA from plant tissues (1987) Anal. Biochem., 163, pp. 16-20Lohse, G., Hedrich, R., Activation of the guard cell plasma membrane H+-ATPase of Vicia faba by plant growth regulators (1992) Planta, 188, pp. 206-214Lowry, O.H., Rosebrough, N.J., Farr, A.L., Randall, R.J., Protein measurement with the phenol reagent (1951) J Biol. Chem., 193, pp. 265-275Ludwig, S.R., Oppenheimer, D.G., Silflow, C.D., Snustad, D.P., Characterization of the α-tubulin gene family of Arabidopsis thaliana (1987) Proc. Natl. Acad Sci. USA, 84, pp. 5833-5837Lüttge, U., Higinbotham, N., (1979) Transport in Plants, , Berlin: Springer-VeriagMichelet, B., Lukaszewicz, M., Dupriez, V., Boutry, M., A plant plasma membrane proton-ATPase gene is regulated by development and environment and shows signs of a translational regulation (1994) Plant Cell, 6, pp. 1375-1389Miller, H., Practical aspects of preparing phage and plasmid DNA: Growth, maintenance and storage of bacteria and bacteriophage (1987) Methods Enzymol., 152, pp. 145-170Moriau, L., Bogaerts, P., Jonniaux, J.-L., Boutry, M., Identification and characterization of a second plasma membrane H+-ATPase gene subfamily in Nicotiana plumbaginifolia (1993) Plant Mol. Biol., 21, pp. 955-963Newman, T.C., Ohme-Takagi, M., Taylor, C.B., Green, P.J., DST sequences, highly conserved among plant SAUR genes, target reporter transcripts for rapid decay in tobacco (1993) Plant Cell, 5, pp. 701-714Noubhani, A.M., Sakr, S., Denis, M.H., Delrot, S., Tran scriptional and post-transcriptional control of the plant plasma membrane H+-ATPase by mechanical treatments (1996) Biochim. Biophys. Acta, , in pressPalmgren, M.G., Capturing of host DNA by a plant retroelement: Bs1 encodes plasma membrane H+-ATPase domains (1994) Plant Mol. Biol., 25, pp. 137-140Palmgren, M.G., Christensen, G., Functional comparisons between plant plasma membrane H+-ATPase isoforms expressed in yeast (1994) J. Biol. Chem., 269, pp. 3027-3033Pardo, J.M., Serrano, R., Structure of a plasma membrane H+-ATPase gene from the plant Arabidopsis thaliana (1989) J. Biol. Chem., 264, pp. 8557-8562Parets-Soler, A., Pardo, J.M., Serrano, R., Immunolocalization of plasma membrane H+-ATPase (1990) Plant Physiol., 93, pp. 1654-1658Parets-Soler, A., Cañas, L., Beltrán, J.P., Spatial and temporal induction of H+-ATPase during flower development in Pisum sativum L (1993) Plant Sci, 92, pp. 57-67Perez, C., Michelet, B., Ferrant, V., Bogaerts, P., Boutry, M., Differential expression within a three-gene subfamily encoding a plasma membrane proton ATPase in Nicotiana plumbaginifolia (1992) J. Biol. Chem., 267, pp. 1204-1211Raven, P.H., Evert, R.F., Eichhorn, S.E., (1986) Biology of Plants, , New York: Worth PublishersRayle, D.L., Cleland, R.E., Control of plant cell enlargement by hydrogen ions (1977) Curr. Top Dev Biol, 11, pp. 187-214Rayle, D.L., Cleland, R.E., The acid growth theory of auxininduced cell elongation is alive and well (1992) Plant Physiol., 99, pp. 1271-1274Roldán, M., Donaire, J.P., Pardo, J.M., Serrano, R., Regulation of root plasma membrane H+-ATPase in sunflower seedlings (1991) Plant Sci, 79, pp. 163-172Rück, A., Palme, K., Venis, M.A., Napier, R.M., Felle, H.H., Patch-clamp analysis establishes a role for an auxin binding protein in the auxin stimulation of plasma membrane current in Zea mays protoplasts (1993) Plant J., 4, pp. 41-46Samuels, A.L., Fernando, M., Glass, A.D.M., Immunofluorescent localization of plasma membrane H+-ATPase in barley roots and effects of K+ nutrition (1992) Plant Physiol., 99, pp. 1509-1514Sanger, F., Nicklen, S., Coulson, A.R., DNA sequencing with chain-terminating inhibitors (1977) Proc. Natl. Acad. Sci. USA, 74, pp. 5463-5467Santoni, V., Vansuyt, G., Rossignol, M., The changing sensitivity to auxin of the plasma-membrane H+-ATPase: Relationship between plant development and ATPase content of membranes (1991) Planta, 185, pp. 227-232Serrano, R., Structure and function of plasma membrane ATPase (1989) Annu. Rev Plant Physiol. Plant Mol. Biol., 40, pp. 61-94Serrano, R., Structure, function and regulation of plasma membrane H+-ATPase (1993) FEBS Lett., 325, pp. 108-111Serrano, R., Kielland-Brandt, M.C., Fink, G., Yeast plasma membrane ATPase is essential for growth and has homology with (Na+ + K+), K+ and Ca2+-ATPases (1986) Nature, 319, pp. 689-693Shcherban, T.Y., Shi, J., Durachko, D.M., Guiltinan, M.J., McQueen-Mason, S.J., Shie, M., Cosgrove, D.J., Molecular cloning and sequence analysis of expansins, a highly conserved, muitigene family of proteins that mediate cell wall extension in plants (1995) Proc Natl. Acad. Sci. USA, 92, pp. 9245-9249Sussman, M.R., Molecular analysis of proteins in the plant plasma membrane (1994) Annu. Rev. Plant Physiol. Plant Mol. Biol., 45, pp. 211-234Takahashi, Y., Sakai, T., Ishida, S., Nagata, T., Identification of auxin-responsive elements of parB and their expression in apices of shoot and root (1995) Proc Natl. Acad. Sci. USA, 92, pp. 6359-6363Vesper, M.J., Evans, M.L., Nonhormonal induction of H+ efflux from plant tissues and its correlation with growth (1979) Proc. Natl Acad Sci USA, 76, pp. 6366-6370Villalba, J.M., Lützelschwab, M., Serrano, R., Immunolocalization of plasma membrane H+-ATPase in maize coleoptiles and enclosed leaves (1991) Planta, 185, pp. 458-461Wada, M., Takano, M., Kasamo, K., Nucleotide sequence of a complementary DNA encoding plasma membrane H+-ATPase from rice (Oryza sativa L.) (1992) Plant Physiol., 99, pp. 794-795Wimmers, L.E., Ewing, N.N., Bennett, A.B., Higher plant Ca2+-ATPase: Primary structure and regulation of mRNA abundance by salt (1992) Proc. Natl. Acad. Sci. USA, 89, pp. 9205-9209