Current perspectives on the hormonal control of seed development in Arabidopsis and maize: a focus on auxin.

The seed represents the unit of reproduction of flowering plants, capable of developing into another plant, and to ensure the survival of the species under unfavorable environmental conditions. It is composed of three compartments: seed coat, endosperm and embryo. Proper seed development depends on the coordination of the processes that lead to seed compartments differentiation, development and maturation.Funded by the Ministry for Education and University, Italy(FIRB grant no. RBFR08UG7)Postprint (published version

Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters

[EN] Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker's yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive structure-function studies for ion transporting proteins. Moreover, yeast can also be used as a high-throughput platform for the identification of genes that confer stress tolerance and for the study of protein-protein interactions. In this review, we summarize advances regarding potassium and sodium transport that have been discovered using the yeast model system, the state-of-the-art of the available techniques and the future directions and opportunities in this field.This work was supported by the Spanish Ministry of Economy and Competitiveness (BIO201677776-P and BIO2016-81957-REDT) and the Valencian Government (AICO/2018/300)Locascio, AAM.; Andrés-Colás, N.; Mulet, JM.; Yenush, L. (2019). Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters. International Journal of Molecular Sciences. 20(9):1-37. https://doi.org/10.3390/ijms20092133S137209Schroeder, J. I. (2003). Knockout of the guard cell K+out channel and stomatal movements. Proceedings of the National Academy of Sciences, 100(9), 4976-4977. doi:10.1073/pnas.1031801100Hurst, A. C., Meckel, T., Tayefeh, S., Thiel, G., & Homann, U. (2004). Trafficking of the plant potassium inward rectifier KAT1 in guard cell protoplasts of Vicia faba. The Plant Journal, 37(3), 391-397. doi:10.1046/j.1365-313x.2003.01972.xBRAG, H. (1972). The Influence of Potassium on the Transpiration Rate and Stomatal Opening in Triticum aestivum andPisum sativum. Physiologia Plantarum, 26(2), 250-257. doi:10.1111/j.1399-3054.1972.tb08553.xMohd Zain, N. A., & Ismail, M. R. (2016). Effects of potassium rates and types on growth, leaf gas exchange and biochemical changes in rice (Oryza sativa) planted under cyclic water stress. Agricultural Water Management, 164, 83-90. doi:10.1016/j.agwat.2015.09.022Hooymans, J. J. M. (1969). The influence of the transpiration rate on uptake and transport of potassium ions in barley plants. Planta, 88(4), 369-371. doi:10.1007/bf00387465Ohnishi, J., Flügge, U.-I., Heldt, H. W., & Kanai, R. (1990). Involvement of Na+ in Active Uptake of Pyruvate in Mesophyll Chloroplasts of Some C4 Plants. Plant Physiology, 94(3), 950-959. doi:10.1104/pp.94.3.950Amtmann, A., & Sanders, D. (1998). Mechanisms of Na+ Uptake by Plant Cells. Advances in Botanical Research, 75-112. doi:10.1016/s0065-2296(08)60310-9Horie, T., Costa, A., Kim, T. H., Han, M. J., Horie, R., Leung, H.-Y., … Schroeder, J. I. (2007). Rice OsHKT2;1 transporter mediates large Na+ influx component into K+-starved roots for growth. The EMBO Journal, 26(12), 3003-3014. doi:10.1038/sj.emboj.7601732Wu, H. (2018). Plant salt tolerance and Na+ sensing and transport. The Crop Journal, 6(3), 215-225. doi:10.1016/j.cj.2018.01.003Pyo, Y. J., Gierth, M., Schroeder, J. I., & Cho, M. H. (2010). High-Affinity K+ Transport in Arabidopsis: AtHAK5 and AKT1 Are Vital for Seedling Establishment and Postgermination Growth under Low-Potassium Conditions. Plant Physiology, 153(2), 863-875. doi:10.1104/pp.110.154369Maathuis, F. J., & Sanders, D. (1994). Mechanism of high-affinity potassium uptake in roots of Arabidopsis thaliana. Proceedings of the National Academy of Sciences, 91(20), 9272-9276. doi:10.1073/pnas.91.20.9272Anderson, J. A., Huprikar, S. S., Kochian, L. V., Lucas, W. J., & Gaber, R. F. (1992). Functional expression of a probable Arabidopsis thaliana potassium channel in Saccharomyces cerevisiae. Proceedings of the National Academy of Sciences, 89(9), 3736-3740. doi:10.1073/pnas.89.9.3736Gassmann, W., & Schroeder, J. I. (1994). Inward-Rectifying K+ Channels in Root Hairs of Wheat (A Mechanism for Aluminum-Sensitive Low-Affinity K+ Uptake and Membrane Potential Control). Plant Physiology, 105(4), 1399-1408. doi:10.1104/pp.105.4.1399Cao, Y., Ward, J. M., Kelly, W. B., Ichida, A. M., Gaber, R. F., Anderson, J. A., … Crawford, N. M. (1995). Multiple Genes, Tissue Specificity, and Expression-Dependent Modulation Contribute to the Functional Diversity of Potassium Channels in Arabidopsis thaliana. Plant Physiology, 109(3), 1093-1106. doi:10.1104/pp.109.3.1093Müller-Röber, B., Ellenberg, J., Provart, N., Willmitzer, L., Busch, H., Becker, D., … Hedrich, R. (1995). Cloning and electrophysiological analysis of KST1, an inward rectifying K+ channel expressed in potato guard cells. The EMBO Journal, 14(11), 2409-2416. doi:10.1002/j.1460-2075.1995.tb07238.xLebaudy, A., Véry, A.-A., & Sentenac, H. (2007). K+channel activity in plants: Genes, regulations and functions. FEBS Letters, 581(12), 2357-2366. doi:10.1016/j.febslet.2007.03.058Véry, A.-A., Nieves-Cordones, M., Daly, M., Khan, I., Fizames, C., & Sentenac, H. (2014). Molecular biology of K+ transport across the plant cell membrane: What do we learn from comparison between plant species? Journal of Plant Physiology, 171(9), 748-769. doi:10.1016/j.jplph.2014.01.011Schachtman, D., Schroeder, J., Lucas, W., Anderson, J., & Gaber, R. (1992). Expression of an inward-rectifying potassium channel by the Arabidopsis KAT1 cDNA. Science, 258(5088), 1654-1658. doi:10.1126/science.8966547Gaymard, F., Cerutti, M., Horeau, C., Lemaillet, G., Urbach, S., Ravallec, M., … Thibaud, J.-B. (1996). The Baculovirus/Insect Cell System as an Alternative toXenopusOocytes. Journal of Biological Chemistry, 271(37), 22863-22870. doi:10.1074/jbc.271.37.22863Su, H., Balderas, E., Vera-Estrella, R., Golldack, D., Quigley, F., Zhao, C., … Bohnert, H. J. (2003). Plant Molecular Biology, 52(5), 967-980. doi:10.1023/a:1025445612244Paynter, J. J., Andres-Enguix, I., Fowler, P. W., Tottey, S., Cheng, W., Enkvetchakul, D., … Tucker, S. J. (2010). Functional Complementation and Genetic Deletion Studies of KirBac Channels. Journal of Biological Chemistry, 285(52), 40754-40761. doi:10.1074/jbc.m110.175687Bichet, D., Lin, Y.-F., Ibarra, C. A., Huang, C. S., Yi, B. A., Jan, Y. N., & Jan, L. Y. (2004). Evolving potassium channels by means of yeast selection reveals structural elements important for selectivity. Proceedings of the National Academy of Sciences, 101(13), 4441-4446. doi:10.1073/pnas.0401195101Zaks-Makhina, E., Kim, Y., Aizenman, E., & Levitan, E. S. (2004). Novel Neuroprotective K+ Channel Inhibitor Identified by High-Throughput Screening in Yeast. Molecular Pharmacology, 65(1), 214-219. doi:10.1124/mol.65.1.214Paynter, J. J., Sarkies, P., Andres-Enguix, I., & Tucker, S. J. (2008). Genetic selection of activatory mutations in KcsA. Channels, 2(6), 413-418. doi:10.4161/chan.2.6.6874Yenush, L. (2016). Potassium and Sodium Transport in Yeast. Yeast Membrane Transport, 187-228. doi:10.1007/978-3-319-25304-6_8Gaber, R. F., Styles, C. A., & Fink, G. R. (1988). TRK1 encodes a plasma membrane protein required for high-affinity potassium transport in Saccharomyces cerevisiae. Molecular and Cellular Biology, 8(7), 2848-2859. doi:10.1128/mcb.8.7.2848Ko, C. H., & Gaber, R. F. (1991). TRK1 and TRK2 encode structurally related K+ transporters in Saccharomyces cerevisiae. Molecular and Cellular Biology, 11(8), 4266-4273. doi:10.1128/mcb.11.8.4266Durell, S. R., & Guy, H. R. (1999). Structural Models of the KtrB, TrkH, and Trk1,2 Symporters Based on the Structure of the KcsA K+ Channel. Biophysical Journal, 77(2), 789-807. doi:10.1016/s0006-3495(99)76932-8Kuroda, T., Bihler, H., Bashi, E., Slayman, C. L., & Rivetta, A. (2004). Chloride Channel Function in the Yeast TRK-Potassium Transporters. Journal of Membrane Biology, 198(3), 177-192. doi:10.1007/s00232-004-0671-1Zayats, V., Stockner, T., Pandey, S. K., Wörz, K., Ettrich, R., & Ludwig, J. (2015). A refined atomic scale model of the Saccharomyces cerevisiae K+-translocation protein Trk1p combined with experimental evidence confirms the role of selectivity filter glycines and other key residues. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1848(5), 1183-1195. doi:10.1016/j.bbamem.2015.02.007Haro, R., & Rodrı́guez-Navarro, A. (2002). Molecular analysis of the mechanism of potassium uptake through the TRK1 transporter of Saccharomyces cerevisiae. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1564(1), 114-122. doi:10.1016/s0005-2736(02)00408-xAriño, J., Ramos, J., & Sychrová, H. (2010). Alkali Metal Cation Transport and Homeostasis in Yeasts. Microbiology and Molecular Biology Reviews, 74(1), 95-120. doi:10.1128/mmbr.00042-09Ruiz, A., & Ariño, J. (2007). Function and Regulation of the Saccharomyces cerevisiae ENA Sodium ATPase System. Eukaryotic Cell, 6(12), 2175-2183. doi:10.1128/ec.00337-07Haro, R., Garciadeblas, B., & Rodriguez-Navarro, A. (1991). A novel P-type ATPase from yeast involved in sodium transport. FEBS Letters, 291(2), 189-191. doi:10.1016/0014-5793(91)81280-lBenito, B., Garciadeblás, B., & Rodrı́guez-Navarro, A. (2002). Potassium- or sodium-efflux ATPase, a key enzyme in the evolution of fungi The GenBank accession numbers for the sequences reported in this paper are: Pleurotus ostreatus ENA1, AJ420741; Phycomyces blakesleeanus ENA1, AJ420742; Ph. blakesleeanus PCA1, AJ420743; Blakeslea trispora ENA1, AJ420744; B. trispora BCA1, AJ420745; B. trispora BCA2, AJ420746. Microbiology, 148(4), 933-941. doi:10.1099/00221287-148-4-933Palmgren, M. G., & Nissen, P. (2011). P-Type ATPases. Annual Review of Biophysics, 40(1), 243-266. doi:10.1146/annurev.biophys.093008.131331Nakamura, N., Tanaka, S., Teko, Y., Mitsui, K., & Kanazawa, H. (2004). Four Na+/H+Exchanger Isoforms Are Distributed to Golgi and Post-Golgi Compartments and Are Involved in Organelle pH Regulation. Journal of Biological Chemistry, 280(2), 1561-1572. doi:10.1074/jbc.m410041200Ohgaki, R., Nakamura, N., Mitsui, K., & Kanazawa, H. (2005). Characterization of the ion transport activity of the budding yeast Na+/H+ antiporter, Nha1p, using isolated secretory vesicles. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1712(2), 185-196. doi:10.1016/j.bbamem.2005.03.011Ketchum, K. A., Joiner, W. J., Sellers, A. J., Kaczmarek, L. K., & Goldstein, S. A. N. (1995). A new family of outwardly rectifying potassium channel proteins with two pore domains in tandem. Nature, 376(6542), 690-695. doi:10.1038/376690a0Maresova, L., Urbankova, E., Gaskova, D., & Sychrova, H. (2006). Measurements of plasma membrane potential changes inSaccharomyces cerevisiaecells reveal the importance of the Tok1 channel in membrane potential maintenance. FEMS Yeast Research, 6(7), 1039-1046. doi:10.1111/j.1567-1364.2006.00140.xAhmed, A., Sesti, F., Ilan, N., Shih, T. M., Sturley, S. L., & Goldstein, S. A. . (1999). A Molecular Target for Viral Killer Toxin. Cell, 99(3), 283-291. doi:10.1016/s0092-8674(00)81659-1Cagnac, O., Leterrier, M., Yeager, M., & Blumwald, E. (2007). Identification and Characterization of Vnx1p, a Novel Type of Vacuolar Monovalent Cation/H+Antiporter ofSaccharomyces cerevisiae. Journal of Biological Chemistry, 282(33), 24284-24293. doi:10.1074/jbc.m703116200Petrezselyova, S., Kinclova-Zimmermannova, O., & Sychrova, H. (2013). Vhc1, a novel transporter belonging to the family of electroneutral cation–Cl− cotransporters, participates in the regulation of cation content and morphology of Saccharomyces cerevisiae vacuoles. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1828(2), 623-631. doi:10.1016/j.bbamem.2012.09.019Andre, B., & Scherens, B. (1995). The Yeast YBR235W Gene Encodes a Homolog of the Mammalian Electroneutral Na+-(K+)-Cl− Cotransporter Family. Biochemical and Biophysical Research Communications, 217(1), 150-153. doi:10.1006/bbrc.1995.2757Nass, R., & Rao, R. (1998). Novel Localization of a Na+/H+Exchanger in a Late Endosomal Compartment of Yeast. Journal of Biological Chemistry, 273(33), 21054-21060. doi:10.1074/jbc.273.33.21054Long, S. B. (2005). Crystal Structure of a Mammalian Voltage-Dependent Shaker Family K+ Channel. Science, 309(5736), 897-903. doi:10.1126/science.1116269Pilot, G., Lacombe, B., Gaymard, F., Chérel, I., Boucherez, J., Thibaud, J.-B., & Sentenac, H. (2000). Guard Cell Inward K+Channel Activity inArabidopsisInvolves Expression of the Twin Channel Subunits KAT1 and KAT2. Journal of Biological Chemistry, 276(5), 3215-3221. doi:10.1074/jbc.m007303200Saito, S., Hoshi, N., Zulkifli, L., Widyastuti, S., Goshima, S., Dreyer, I., & Uozumi, N. (2017). Identification of regions responsible for the function of the plant K+ channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes. Channels, 11(6), 510-516. doi:10.1080/19336950.2017.1372066Nakamura, R. L., Anderson, J. A., & Gaber, R. F. (1997). Determination of Key Structural Requirements of a K+Channel Pore. Journal of Biological Chemistry, 272(2), 1011-1018. doi:10.1074/jbc.272.2.1011Nakamura, R. L., & Gaber, R. F. (2009). Ion selectivity of the Kat1 K+channel pore. Molecular Membrane Biology, 26(5-7), 293-308. doi:10.1080/09687680903188332Kochian, L. V., Garvin, D. F., Shaff, J. E., Chilcott, T. C., & Lucas, W. J. (1993). Towards an understanding of the molecular basis of plants K+ transport: Characterization of cloned K+ transport cDNAs. Plant and Soil, 155-156(1), 115-118. doi:10.1007/bf00024997Lai, H. C., Grabe, M., Jan, Y. N., & Jan, L. Y. (2005). The S4 Voltage Sensor Packs Against the Pore Domain in the KAT1 Voltage-Gated Potassium Channel. Neuron, 47(3), 395-406. doi:10.1016/j.neuron.2005.06.019Su, Y.-H., North, H., Grignon, C., Thibaud, J.-B., Sentenac, H., & Véry, A.-A. (2005). Regulation by External K+ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range. The Plant Cell, 17(5), 1532-1548. doi:10.1105/tpc.104.030551Obata, T., Kitamoto, H. K., Nakamura, A., Fukuda, A., & Tanaka, Y. (2007). Rice Shaker Potassium Channel OsKAT1 Confers Tolerance to Salinity Stress on Yeast and Rice Cells. Plant Physiology, 144(4), 1978-1985. doi:10.1104/pp.107.101154Hirsch, R. E. (1998). A Role for the AKT1 Potassium Channel in Plant Nutrition. Science, 280(5365), 918-921. doi:10.1126/science.280.5365.918Ahn, S. J., Shin, R., & Schachtman, D. P. (2004). Expression of KT/KUP Genes in Arabidopsis and the Role of Root Hairs in K+ Uptake. Plant Physiology, 134(3), 1135-1145. doi:10.1104/pp.103.034660Gierth, M., Mäser, P., & Schroeder, J. I. (2005). The Potassium Transporter AtHAK5 Functions in K+ Deprivation-Induced High-Affinity K+ Uptake and AKT1 K+ Channel Contribution to K+ Uptake Kinetics in Arabidopsis Roots. Plant Physiology, 137(3), 1105-1114. doi:10.1104/pp.104.057216Ros, R., Lemaillet, G., Fonrouge, A. G., Daram, P., Enjuto, M., Salmon, J. M., … Sentenac, H. (1999). Molecular determinants of the Arabidopsis AKT1 K+ channel ionic selectivity investigated by expression in yeast of randomly mutated channels. Physiologia Plantarum, 105(3), 459-468. doi:10.1034/j.1399-3054.1999.105310.xHartje, S., Zimmermann, S., Klonus, D., & Mueller-Roeber, B. (2000). Functional characterisation of LKT1, a K + uptake channel from tomato root hairs, and comparison with the closely related potato inwardly rectifying K + channel SKT1 after expression in Xenopus oocytes. Planta, 210(5), 723-731. doi:10.1007/s004250050673BOSCARI, A., CLÉMENT, M., VOLKOV, V., GOLLDACK, D., HYBIAK, J., MILLER, A. J., … FRICKE, W. (2009). Potassium channels in barley: cloning, functional characterization and expression analyses in relation to leaf growth and development. Plant, Cell & Environment, 32(12), 1761-1777. doi:10.1111/j.1365-3040.2009.02033.xSchleyer, M., & Bakker, E. P. (1993). Nucleotide sequence and 3’-end deletion studies indicate that the K(+)-uptake protein kup from Escherichia coli is composed of a hydrophobic core linked to a large and partially essential hydrophilic C terminus. Journal of Bacteriology, 175(21), 6925-6931. doi:10.1128/jb.175.21.6925-6931.1993Bañuelos, M. A., Klein, R. D., Alexander-Bowman, S. J., & Rodríguez-Navarro, A. (1995). A potassium transporter of the yeast Schwanniomyces occidentalis homologous to the Kup system of Escherichia coli has a high concentrative capacity. The EMBO Journal, 14(13), 3021-3027. doi:10.1002/j.1460-2075.1995.tb07304.xSanta-María, G. E., Rubio, F., Dubcovsky, J., & Rodríguez-Navarro, A. (1997). The HAK1 gene of barley is a member of a large gene family and encodes a high-affinity potassium transporter. The Plant Cell, 9(12), 2281-2289. doi:10.1105/tpc.9.12.2281Nieves-Cordones, M., Alemán, F., Martínez, V., & Rubio, F. (2010). The Arabidopsis thaliana HAK5 K+ Transporter Is Required for Plant Growth and K+ Acquisition from Low K+ Solutions under Saline Conditions. Molecular Plant, 3(2), 326-333. doi:10.1093/mp/ssp102Rubio, F., Santa-María, G. E., & Rodríguez-Navarro, A. (2000). Cloning of Arabidopsis and barley cDNAs encoding HAK potassium transporters in root and shoot cells. Physiologia Plantarum, 109(1), 34-43. doi:10.1034/j.1399-3054.2000.100106.xRubio, F., Gassmann, W., & Schroeder, J. I. (1995). Sodium-Driven Potassium Uptake by the Plant Potassium Transporter HKT1 and Mutations Conferring Salt Tolerance. Science, 270(5242), 1660-1663. doi:10.1126/science.270.5242.1660Gassmann, W., Rubio, F., & Schroeder, J. I. (1996). Alkali cation selectivity of the wheat root high-affinity potassium transporter HKT1. The Plant Journal, 10(5), 869-882. doi:10.1046/j.1365-313x.1996.10050869.xUozumi, N., Kim, E. J., Rubio, F., Yamaguchi, T., Muto, S., Tsuboi, A., … Schroeder, J. I. (2000). The Arabidopsis HKT1 Gene Homolog Mediates Inward Na+ Currents in Xenopus laevis Oocytes and Na+ Uptake in Saccharomyces cerevisiae. Plant Physiology, 122(4), 1249-1260. doi:10.1104/pp.122.4.1249Rubio, F., Schwarz, M., Gassmann, W., & Schroeder, J. I. (1999). Genetic Selection of Mutations in the High Affinity K+Transporter HKT1 That Define Functions of a Loop Site for Reduced Na+Permeability and Increased Na+Tolerance. Journal of Biological Chemistry, 274(11), 6839-6847. doi:10.1074/jbc.274.11.6839Sunarpi, Horie, T., Motoda, J., Kubo, M., Yang, H., Yoda, K., … Uozumi, N. (2005). Enhanced salt tolerance mediated by AtHKT1 transporter-induced Na+ unloading from xylem vessels to xylem parenchyma cells. The Plant Journal, 44(6), 928-938. doi:10.1111/j.1365-313x.2005.02595.xFairbairn, D. J., Liu, W., Schachtman, D. P., Gomez-Gallego, S., Day, S. R., & Teasdale, R. D. (2000). Plant Molecular Biology, 43(4), 515-525. doi:10.1023/a:1006496402463Horie, T., Yoshida, K., Nakayama, H., Yamada, K., Oiki, S., & Shinmyo, A. (2001). Two types of HKT transporters with different properties of Na+ and K+ transport in Oryza sativa. The Plant Journal, 27(2), 129-138. doi:10.1046/j.1365-313x.2001.01077.xWang, T.-B., Gassmann, W., Rubio, F., Schroeder, J. I., & Glass, A. D. M. (1998). Rapid Up-Regulation of HKT1, a High-Affinity Potassium Transporter Gene, in Roots of Barley and Wheat following Withdrawal of Potassium. Plant Physiology, 118(2), 651-659. doi:10.1104/pp.118.2.651Safiarian, M. J., Pertl-Obermeyer, H., Lughofer, P., Hude, R., Bertl, A., & Obermeyer, G. (2015). Lost in traffic? The K+ channel of lily pollen, LilKT1, is detected at the endomembranes inside yeast cells, tobacco leaves, and lily pollen. Frontiers in Plant Science, 6. doi:10.3389/fpls.2015.00047Mouline, K. (2002). Pollen tube development and competitive ability are impaired by disruption of a Shaker K+ channel in Arabidopsis. Genes & Development, 16(3), 339-350. doi:10.1101/gad.213902Bihler, H., Eing, C., Hebeisen, S., Roller, A., Czempinski, K., & Bertl, A. (2005). TPK1 Is a Vacuolar Ion Channel Different from the Slow-Vacuolar Cation Channel. Plant Physiology, 139(1), 417-424. doi:10.1104/pp.105.065599Hamamoto, S., Marui, J., Matsuoka, K., Higashi, K., Igarashi, K., Nakagawa, T., … Uozumi, N. (2007). Characterization of a Tobacco TPK-type K+Channel as a Novel Tonoplast K+Channel Using Yeast Tonoplasts. Journal of Biological Chemistry, 283(4), 1911-1920. doi:10.1074/jbc.m708213200Goldstein, S. A. N., Bockenhauer, D., O’Kelly, I., & Zilberberg, N. (2001). Potassium leak channels and the KCNK family of two-p-domain subunits. Nature Reviews Neuroscience, 2(3), 175-184. doi:10.1038/35058574Becker, D., Geiger, D., Dunkel, M., Roller, A., Bertl, A., Latz, A., … Hedrich, R. (2004). AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+-dependent manner. Proceedings of the National Academy of Sciences, 101(44), 15621-15626. doi:10.1073/pnas.0401502101Apse, M. P. (1999). Salt Tolerance Conferred by Overexpression of a Vacuolar Na+/H+ Antiport in Arabidopsis. Science, 285(5431), 1256-1258. doi:10.1126/science.285.5431.1256Gaxiola, R. A., Rao, R., Sherman, A., Grisafi, P., Alper, S. L., & Fink, G. R. (1999). The Arabidopsis thaliana proton transporters, AtNhx1 and Avp1, can function in cation detoxification in yeast. Proceedings of the National Academy of Sciences, 96(4), 1480-1485. doi:10.1073/pnas.96.4.1480Bassil, E., Tajima, H., Liang, Y.-C., Ohto, M., Ushijima, K., Nakano, R., … Blumwald, E. (2011). The Arabidopsis Na+/H+ Antiporters

COP1 destabilizes DELLA proteins in Arabidopsis

DELLA transcriptional regulators are central components in the control of plant growth responses to the environment. This control is considered to be mediated by changes in the metabolism of the hormones gibberellins (GAs), which promote the degradation of DELLAs. However, here we show that warm temperature or shade reduced the stability of a GA-insensitive DELLA allele in Arabidopsis thaliana. Furthermore, the degradation of DELLA induced by the warmth preceded changes in GA levels and depended on the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). COP1 enhanced the degradation of normal and GA-insensitive DELLA alleles when coexpressed in Nicotiana benthamiana. DELLA proteins physically interacted with COP1 in yeast, mammalian, and plant cells. This interaction was enhanced by the COP1 complex partner SUPRESSOR OF phyA-105 1 (SPA1). The level of ubiquitination of DELLA was enhanced by COP1 and COP1 ubiquitinated DELLA proteins in vitro. We propose that DELLAs are destabilized not only by the canonical GA-dependent pathway but also by COP1 and that this control is relevant for growth responses to shade and warm temperature.This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness and Agencia Española de Investigación/Fondo Europeo para el Desarrollo Regional/Unión Europea (grants BIO2016-79133-P to D.A. and BIO2013-46539-R and BIO2016-80551-R to V.R.); the European Union SIGNAT-Research and Innovation Staff Exchange (Grant H2020-MSCA-RISE-2014-644435 to M.A.B., D.A., and J.J.C.); the Argentinian Agencia Nacional de Promoción Científica y Tecnológica (Grant Proyectos de Investigación Científica y Tecnológica-2016-1459 to J.J.C.); Universidad de Buenos Aires (grant 20020170100505BA to J.J.C.); the National Institute of General Medical Sciences of the National Institutes of Health (awards R01GM067837 and R01GM056006 to S.A.K.); the German Research Foundation (DFG) under Germany’s Excellence Strategy/Initiative (Cluster of Excellence on Plant Sciences – Excellence Cluster EXC-2048/1, Project ID 390686111 to M.D.Z.); the International Max Planck Research School of the Max Planck Society; the Universities of Düsseldorf and of Cologne to T.B.; Nordrhein Westfalen Bioeconomy Science Center-FocusLabs CombiCom to N.H. and M.D.Z.; and Ministry of Education, Youth and Sports of the Czech Republic (Project LQ1601 Central European Institute of Technology 2020 to B.B. and M.C.). N.B.-T., E.I., and M.G.-L. were supported by Ministerio de Economía y Competitividad-Formación de Personal Investigador Program fellowships

COP1 destabilizes DELLA proteins in Arabidopsis

DELLA transcriptional regulators are central components in the control of plant growth responses to the environment. This control is considered to be mediated by changes in the metabolism of the hormones gibberellins (GAs), which promote the degradation of DELLAs. However, here we show that warm temperature or shade reduced the stability of a GA-insensitive DELLA allele in Arabidopsis thaliana. Furthermore, the degradation of DELLA induced by the warmth preceded changes in GA levels and depended on the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). COP1 enhanced the degradation of normal and GAinsensitive DELLA alleles when coexpressed in Nicotiana benthamiana. DELLA proteins physically interacted with COP1 in yeast, mammalian, and plant cells. This interaction was enhanced by the COP1 complex partner SUPRESSOR OF phyA-105 1 (SPA1). The level of ubiquitination of DELLA was enhanced by COP1 and COP1 ubiquitinated DELLA proteins in vitro. We propose that DELLAs are destabilized not only by the canonical GA-dependent pathway but also by COP1 and that this control is relevant for growth responses to shade and warm temperature.Fil: Blanco Touriñán, Noel. Universidad Politécnica de Valencia; EspañaFil: Legris, Martina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Minguet, Eugenio G.. Universidad Politécnica de Valencia; EspañaFil: Costigliolo Rojas, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Nohales, María A.. University of Southern California; Estados UnidosFil: Iniesto, Elisa. Consejo Superior de Investigaciones Científicas; EspañaFil: García León, Marta. Consejo Superior de Investigaciones Científicas; EspañaFil: Pacín, Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Heucken, Nicole. Universitat Dusseldorf; AlemaniaFil: Blomeier, Tim. Universitat Dusseldorf; AlemaniaFil: Locascio, Antonella. Universidad Politécnica de Valencia; EspañaFil: Cerný, Martin. Mendel University in Brno; República ChecaFil: Esteve Bruna, David. Universidad Politécnica de Valencia; EspañaFil: Díez Díaz, Mónica. Univerdiad Catolica de Valencia; EspañaFil: Brzobohatý, Bretislav. Mendel University in Brno; República ChecaFil: Frerigmann, Henning. Max Planck Institute for Plant Breeding Research; AlemaniaFil: Zurbriggen, Matías D.. Universitat Dusseldorf; AlemaniaFil: Kay, Steve A.. University of Southern California; Estados UnidosFil: Rubio, Vicente. Consejo Superior de Investigaciones Científicas; EspañaFil: Blázquez, Miguel A.. Universidad Politécnica de Valencia; EspañaFil: Casal, Jorge José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Alabadí, David. Universidad Politécnica de Valencia; Españ

Genome Wide Binding Site Analysis Reveals Transcriptional Coactivation of Cytokinin-Responsive Genes by DELLA Proteins

[EN] The ability of plants to provide a plastic response to environmental cues relies on the connectivity between signaling pathways. DELLA proteins act as hubs that relay environmental information to the multiple transcriptional circuits that control growth and development through physical interaction with transcription factors from different families. We have analyzed the presence of one DELLA protein at the Arabidopsis genome by chromatin immunoprecipitation coupled to large-scale sequencing and we find that it binds at the promoters of multiple genes. Enrichment analysis shows a strong preference for cis elements recognized by specific transcription factor families. In particular, we demonstrate that DELLA proteins are recruited by type-B ARABIDOPSIS RESPONSE REGULATORS (ARR) to the promoters of cytokinin-regulated genes, where they act as transcriptional co-activators. The biological relevance of this mechanism is underpinned by the necessity of simultaneous presence of DELLAs and ARRs to restrict root meristem growth and to promote photomorphogenesis.This work was funded by grants BIO2007-60923 and BIO2010-15071 from the Spanish Ministry of Economy and Innovation (MAB); grant ERC-2011-StG_20101109 from the European Research Council (JUL); grants BB/J/00426X/1 and BB/E022618/1 from the Biotechnology and Biological Sciences Research Council (SGT); the Professorial Research Fellowship award BB/G023972/1 from the Biotechnology and Biological Sciences Research Council (KH and MJB); and grant FP7-311929 from the European Union (RPB). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Marín-De La Rosa, NA.; Pfeiffer, A.; Hill, K.; Locascio ., AAM.; Bhalerao, R.; Miskolczi, P.; Grønlund, A.... (2015). Genome Wide Binding Site Analysis Reveals Transcriptional Coactivation of Cytokinin-Responsive Genes by DELLA Proteins. PLoS Genetics. 11(7):1-20. https://doi.org/10.1371/journal.pgen.100533712011

Genomic analysis of DELLA protein activity

[EN] Changes in gene expression are the main outcome of hormone signaling cascades that widely control plant physiology. In the case of the hormones gibberellins, the transcriptional control is exerted through the activity of the DELLA proteins, which act as negative regulators in the signaling pathway. This review focuses on recent transcriptomic approaches in the context of gibberellin signaling, which have provided useful information on new processes regulated by these hormones such as the regulation of photosynthesis and gravitropism. Moreover, the enrichment of specific cis-elements among DELLA primary targets has also helped extend the view that DELLA proteins regulate gene expression through the interaction with multiple transcription factors from different families.This study was supported by the Italian Ministry of Education, University, and Research (MIUR) [FIRB Progetto Giovani fellowship to A. L.]; the Spanish Ministry of Science and Innovation [grant Nos. BIO2010-15071 and CSD2007-00057]; the Generalitat Valenciana [grant Nos. ACOMP/2012/251 and PROMETEO/2010/020].Locascio, AAM.; Blazquez Rodriguez, MA.; Alabadí Diego, D. (2013). Genomic analysis of DELLA protein activity. Plant and Cell Physiology. 54(8):1229-1237. https://doi.org/10.1093/pcp/pct082S1229123754

Vernalization downregulates Flowering Locus C in Cichorium intybus

Since proper timing of flowering is critical for the survival of plant species, plants have evolved a complex genetic network to regulate their transition to flowering in response to endogenous signals and environmental cues. In winter annuals ecotypes of Arabidopsis, a flowering repressor, FLOWERING LOCUS C (FLC), a MADS box transcription factor, is expressed at such level as to inhibit flowering in the first growing season. FLC expression is enhanced by FRIGIDA (FRI) to levels that inhibit the transition to flowering by repressing the expression of the genes often referred to as Floral Pathways Integrators. The main process promoting flowering by the repression of FLC is the vernalization and the duration of cold has been shown to be proportional to the degree of down-regulation of FLC; such repression is maintained for the rest of the plant life even after cold exposure ends, but is restored after meiosis. The repression involves epigenetically stable modifications in FLC chromatin that include a H3 Lys27 trimethylation (H3K27me3) and a H3 Lys9 trimethylation, (Sung et al, 2006). Interestingly, for the light-dependent, autonomous and GA integration and meristematic pathways, comparative genetic approaches show that flowering time genes are conserved between Arabidopsis and a large range of crop species, including legumes and cereals. By contrast, the vernalization pathway seems to be only partially conserved, since FLC and FRI were not characterized in dicots other than Brassicaceae, and recently in sugar beet, vitis and tomato. Wild chicory (Cichorium intybus L.) is a biennial species which requires vernalization to flower. In Italy different types of chicory (the so called Italian red and variegate types) have been selected by farmers as leafy vegetable. These types show quite different classes of precocity in relation to flowering. Given the high heterogeneity, in regard to flowering, manifested by plants belonging to the same variety, the "control" of the switch by agronomical procedures results difficult. The knowledge about the genetic control of flowering time in chicory could be useful to enhance the vegetative phase and then, increase the productivity of the crop. In our study, we are investigating the molecular basis that regulate the switch to flower in chicory by vernalization, to verify whether such mechanism is the same that controls flowering in Arabidopsis, and, finally, to address the diversity of the classes of precocity to one of the cases known for this model plant. We isolated FLC homologues from chicory and characterized their expression patterns in plant tissues and in response to vernalization. We also studied the pattern of cytosine methylation in chicory genomic DNA in response to vernalization. In addition, the vernalization-mediated decrease of FLC transcript was related with changes in SAM morphology. Biological function of CiFLC has been studied by AtFRIflc3 complementation. Up to now our result indicate that arabidopsis and chicory share homologies in regulating FLC expression in the vernalization response, but the absence of complementation of the mutant suggest a disagree in biological function of CiFLC or a loss of function of the transgene in Arabidopsis genetic background. Further analysis will be conducted to define if the machinery in FLC regulation and its biological function is shared between the two species. For this purpose, chicory mutants will be generated. Other aim of this work has been the identification of FLC genomic sequences in chicory. For this purpose, genome walking technique was used. Knowledge of the genomic sequence of CiFLC will allow comparing the regulative regions with those of AtFLC and performing experiments of chromosome hybridization (i.e. FISH). The goal is identify the number of copies of the gene and characterize its position within the chromosomes. With these results we will be able to formulate hypothesis about the evolution of FLC in Cichorium intybus

Current perspectives on the hormonal control of seed development in Arabidopsis and maize: a focus on auxin

The seed represents the unit of reproduction of flowering plants, capable of developing into another plant, and to ensure the survival of the species under unfavorable environmental conditions. It is composed of three compartments: seed coat, endosperm and embryo. Proper seed development depends on the coordination of the processes that lead to seed compartments differentiation, development and maturation. The coordination of these processes is based on the constant transmission/perception of signals by the three compartments. Phytohormones constitute one of these signals; gradients of hormones are generated in the different seed compartments, and their ratios comprise the signals that induce/inhibit particular processes in seed development. Among the hormones, auxin seems to exert a central role, as it is the only one in maintaining high levels of accumulation from fertilization to seed maturation. The gradient of auxin generated by its PIN carriers affects several processes of seed development, including pattern formation, cell division and expansion. Despite the high degree of conservation in the regulatory mechanisms that lead to seed development within the Spermatophytes, remarkable differences exist during seed maturation between Monocots and Eudicots species. For instance, in Monocots the endosperm persists until maturation, and constitutes an important compartment for nutrients storage, while in Eudicots it is reduced to a single cell layer, as the expanding embryo gradually replaces it during the maturation. This review provides an overview of the current knowledge on hormonal control of seed development, by considering the data available in two model plants: Arabidopsis thaliana, for Eudicots and Zea mays L., for Monocots. We will emphasize the control exerted by auxin on the correct progress of seed development comparing, when possible, the two species.Antonella Locascio, Irma Roig-Villanova, and Jamila Bernardi were funded by the Ministry for Education and University, Italy (FIRB grant no. RBFR08UG7).Peer reviewedPeer Reviewe

Regulation of flowering time by vernalization in Cichorium intybus

In biennal and winter annual ecotypes of Arabidopsis thaliana, flowering is typically blocked in the first growing season. Exposure to prolonged cold temperature, in a process called vernalization, is required to remove this block and permit flowering in the next growing season. In late-flowering ecotypes of Arabidopsis, a flowering repressor, FLOWERING LOCUS C (FLC), is expressed at such high level to inhibit flowering in the first growing season. The delayed flowering is due to dominant alleles of FRIGIDA (FRI) and FLC. FRI elevates expression of FLC to levels that suppress flowering. FLC inhibits the transition to flower by repressing the expression of the genes named Floral Pathways Integrators (such as LFY, FT and SOC1). These genes are able to integrate a balance of stimulations originating from the different pathways inducing flowering and convert these inputs into an induction of FMI (Floral Meristem Integrators) genes, thereby initiating the production of the first floral meristems. Vernalization is the main process promoting flowering by the repression of FLC. Therepression involves epigenetically stable modifications in FLC chromatin that include dimethylation of histone H3 at Lys9 (H3K9) and Lys27 (H3K27). Summer-annual accessions of Arabidopsis flower rapidly without vernalization, due to a mutation in an active FRI allele or due to the presence of a weak FLC allele; in both cases the levels of FLC expression is low compared to the wild type. Wild chicory (Chicoryum intibus L.) is a biennial species which requires vernalization to flower. Chicory is economically important for its use as vegetable and as an industrial raw material to obtain inulin from roots. In Italy different types of chicory (the so called italian red and variegate types) have been selected by farmers. These types show quite different classes of precocity in relation to flowering. We are investigating the molecular mechanism that regulate the switch to flower in chicory, to verify whether such mechanism is the same that controls flowering in Arabidopsis, and finally, address the diversity of the classes of precocity to one of the cases known for this model plant. A cDNA sequences with high homology to AtFLC was identified and a detailed expression analysis was carried out in chicory plants. Transgenic arabidopsis and chicory plants will be produced to functionally characterize this gene

Characterisation of ALS genes in the polyploid species Schoenoplectus mucronatus and implications for resistance management.

BACKGROUND: The polyploid weed Schoenoplectus mucronatus (L.) Palla has evolved target-site resistance to ALS-inhibiting herbicides in Italian rice crops. Molecular and genetic characterisation of the resistance mechanism is relevant to the evolution and management of herbicide resistance. The authors aimed (a) to study the organisation of the target-site loci in two fieldselected S. mucronatus populations with different cross-resistance patterns, (b) to identify the mutations endowing resistance to ALS inhibitors and determine the role of these mutations by using transgenesis and (c) to analyse the implications for the management of the S. mucronatus populations. RESULTS: Two complete ALS genes (ALS1 and ALS2) having an intron and a third partial intronless ALS gene (ALS3) were identified. The presence of multiple ALS genes was confirmed by Southern blot analyses, and ALS loci were characterised by examining cytosine methylation. In S. mucronatus leaves, the transcripts of ALS1, ALS2 and ALS3 were detected. Two mutations endowing resistance (Pro 197 to His and Trp 574 to Leu) were found in both resistant populations, but at different frequencies. Tobacco plants transformed with the two resistant alleles indicated that the Pro 197-to-His substitution conferred resistance to SU and TP herbicides, while the allele with the Trp 574-to-Leu substitution conferred cross-resistance to SU, TP, IMI and PTB herbicides. CONCLUSION: Schoenoplectus mucronatus has multiple ALS genes characterised by methylated sites that can influence the expression profile. The two mutated alleles proved to be responsible for ALS resistance. At population level, the resistance pattern depends on the frequency of various resistant genotypes, and this influences the efficacy of various ALS-inhibiting herbicides. \ua9 2009 Society of Chemical Industry