Group leader: Alonso Rodríguez Navarro - Professor
alonso.rodriguez@upm.es 
+34 91 452 4900 ext.1816 (Lab 277)
Personnel:
The purpose of our research is the construction of plants that are resistant to salinity. Within this general objective, our research has two specific aims: the excluding mechanisms of sodium in the root and the ionic relations between chloroplast and cytoplasm. This research is carried out in three plant species. Physcomitrella patens, Arabidopsis thaliana and rice. A brief description of the research lines is the following: 1. Accumulation of K+ and exclusion of Na+ in the root symplast.
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| 1.1. Basic approach wih Physcomitrella patens.
Physcomitrella is a moss which is being used as a plant model. Our work now in progress has demonstrated that Physcomitrella responds to a model of ionic homeostasis very similar to that of flowering plants and that it expresses the same type of transporters. Moreover we have cloned four transporters of the HAK type of this plant and two AKT type channels, and we have constructed hak1 mutant plants. Continuing in this line, we will construct knockout plant mutants that do not express the other HAK transporters or the AKT1 channels. 1.2. Na+ entrance Using the hak1 knockout Physcomitrella plants we have identified an ionic pathway for K+ and Na+ entry into the roots. According to the kinetic characteristics of cation influxes in these knockout plants we suspect that the influxes are mediated by a CNGC channel. Our next step is aimed to identify this channel. |
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1.3. Improvement of Na+ exclusion by expressing ENA ATPses. The ENA-ATPses are Na+ pumps initially identified by our group in fungi, later on in Physcomitrella and recently in liverworts. Mos of these pumps discriminate little between K+ and Na+, but some fungal pumps transport almost exclusively Na+. Now we are trying to identify ENA-ATPase in liverworts or in characea algae with very high selectivity for Na+. These ATPases will be overexpressed in ena1 ena2 mutants of Physcomitrella plants in parallel with some fungal ENA-ATPases. At this stage we will select the most efficient pump for Physcomitrella. 1.4. Application in Arabidopsis thaliana. The cellular models developed in Physcomitrella in phase 1.1. will be applied to explain the ionic homeostasis in the root symplast of Arabidopsis. Independently, the best ATPases selected in phase 1.2. will be expressed in sos1 mutants of Arabidopsis. Previously, a convenient promoter will be selected to direct the expression to root epidermal and cortical cells 2. Ionic cloroplast-cytoplasm relationships. 2.1. Ion transport in the chloroplast. In salinity conditions, the lighting of the chloroplasts may lead to their destruction. On the other hand, although data are very incomplete, it seems that the chloroplast has some very tight ionic relationships with the cytoplasm and can accumulate fairly high amounts of Na+. Physcomitrella is an ideal plant to study these problems since the techniques to isolate the chloroplasts, or even X ray microanalyses are more attainable in Physcomitrella than in vascular plants.2.2. Role of the NHAD1 transporter. Recently we have cloned the NHAD1 transporter of Physcomitrella, which locates to the internal membrane of the chloroplast envelope and we have found that the transporter is highly conserved from the photosynthetic Stramenophiles to flowering plants. Currently, we are progressing in the construction of nhad1 mutant plants. Relevant results |
During this period most of our research has been addressed to establish Physcomitrella patens, a moss, as a model organism for investigating ionic homeostasis and salinity tolerance in plants. |
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| Our group was a pioneer in the use Saccharomyces cerevisiae and Neurospora crassa as models for K+ and Na+ transport in plants and fungi. The fruits of that approach were multiple and important. However, at this moment fungal models do not have responses to current questions because they are too simple. In fact, as some plant physiologists use to say, plants are not just green yeast. Therefore, we are developing a new model with Physcomitrella patens. This plant has a high rate of homologous recombination and its genomic sequence is public. |
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The first approach was to determine the basic characteristics of K+ and Na+ transport in Physcomitrella. This included the study of many genes encoding K+ and Na+ transport systems, which required the cloning of the cDNAs, the study of their transcript expressions, and the functional expression in yeast cells. We also opened a new line regarding the physiology of the chloroplast and its role during salt stress. For this purpose we cloned the PpNHAD1 antiporter, which is conserved in all photosynthetic organisms. |
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| An interesting result of our research was the cloning of the Na+- ATPase of Physcomitrella and the finding that ATPases of this type have been conserved in all bryophytes. Interestingly, they do not exists in vascular + plants: lycopsids, ferns, or flowering plants. These ATPases are required for growth at pH values above 7.0-7,5 because at the membrane potential of plants and fungi K+ efflux through a channel is impossible and an electroneutral antiport is not functional at those pH values. All this poses an interesting question about the ionic homeostasis of plants growing at pH 8.3, which is a normal pH in calcareous soils. |
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Recent PublicationsFraile-Escanciano, A.; Kamisugi, Y.; Cuming, A.C.; Rodriguez-Navarro, A.; Benito, B. 2010. "The SOS1 transporter of Physcomitrella patens mediates sodium efflux in planta". New Phytologist. 188(3):750-761 Haro, R.; Banuelos, M.A.; Rodriguez-Navarro, A. 2010. "High-affinity sodium uptake in land plants". Plant and Cell Physiology. 51(1):68-79 Rodriguez-Navarro, A.; Benito, B. 2010. "Sodium or potassium efflux ATPase a fungal, bryophyte, and protozoal ATPase". Biochimica et biophysica acta. 1798(10):1841-1853 Benito, B.; Garciadeblas, B.; Perez-Martin, J.; Rodriguez-Navarro, A. 2009. "Growth at High pH and Sodium and Potassium Tolerance in Media above the Cytoplasmic pH Depend on ENA ATPases in Ustilago maydis". Eukaryotic Cell. 8(6):821-829 Fraile-Escanciano, A.; Garciadeblas, B.; Rodriguez-Navarro, A.; Benito, B. 2009. "Role of ENA ATPase in Na+ efflux at high pH in bryophytes". Plant Molecular Biology. 71(6):599-608 Jabnoune, M.; Espeout, S.; Mieulet, D.; Fizames, C.; Verdeil, J.L.; Conejero, G.; Rodriguez-Navarro, A.; Sentenac, H.; Guiderdoni, E.; Abdelly, C.; Very, A.A. 2009. "Diversity in Expression Patterns and Functional Properties in the Rice HKT Transporter Family". Plant Physiology. 150(4):1955-1971 Rodriguez-Navarro, A. 2009. "Sound Research, Unimportant Discoveries: Research, Universities, and Formal Evaluation of Research in Spain". Journal of the American Society for Information Science and Technology. 60(9):1845-1858 Banuelos, M.A.; Haro, R.; Fraile-Escanciano, A.; Rodriguez-Navarro, A. 2008. "Effects of polylinker uATGs on the function of grass HKT1 transporters expressed in yeast cells". Plant and Cell Physiology. 49(7):1128-1132 Barrero-Gil, J.; Rodriguez-Navarro, A.; Benito, B. 2007. "Cloning of the PpNHAD1 transporter of Physcomitrella patens, a chloroplast transporter highly conserved in photosynthetic eukaryotic organisms". Journal of experimental botany. 58:2839-2849 Garciadeblas, B.; Barrero-Gil, J.; Benito, B.; Rodriguez-Navarro, A. 2007. "Potassium transport systems in the moss Physcomitrella patens: pphak1 plants reveal the complexity of potassium uptake". Plant Journal. 52(6):1080-1093 Garciadeblas, B.; Haro, R.; Benito, B. 2007. "Cloning of two SOS1 transporters from the seagrass Cymodocea nodosa. SOS1 transporters from Cymodocea and Arabidopsis mediate potassium uptake in bacteria". Plant Molecular Biology. 63(4):479-490 Imperial, J.; Rodriguez-Navarro, A. 2007. "Usefulness of Hirsch’s h -index to evaluate scientific research in Spain". Scientometrics. 71(2):271-282 |
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Centro de Biotecnología y Genómica de Plantas U.P.M. – I.N.I.A. Parque Científico y Tecnológico de la U.P.M. Campus de Montegancedo
28223 Pozuelo de Alarcón (Madrid) Tel.: +34 91 4524900 ext. 1806 / +34 91 3364539 Fax: +34 91 7157721. Contacto