Role of Na+ transporters HKT1;1 and HKT1;2 in tomato salt tolerance. I. Function loss of cheesmaniae alleles in roots and aerial parts

We wish to thank Elena Sanchez Romero (EEZ-CSIC) for her technical assistance, the Scientific Instrumentation Service at EEZ-CSIC, Granada, for their ICP-OES mineral analysis and Michael O'Shea for proofreading the manuscript. The study was funded by grant AGL201782452-C2-1R (A.B.) and grant AGL2017-82452-C2-2R (M.J.A.), both from the Spanish Ministerio de Ciencia e Innovacion/Agencia Estatal de Investigacion, MCIN/AEI/10.13039/501100011033, and FEDER "Una manera de hacer Europa", as well as grant ACCESP2018 (J.A.T.) from the University of Granada. J.E. was supported by a JAE Intro-CSIC grant, JAEINT_19_00566.We analyzed the physiological impact of function loss on cheesmaniae alleles at the HKT1;1 and HKT1;2 loci in the roots and aerial parts of tomato plants in order to determine the relative contributions of each locus in the different tissues to plant Na+/K+ homeostasis and subsequently to tomato salt tolerance. We generated different reciprocal rootstock/scion combinations with non-silenced, single RNAi-silenced lines for ScHKT1;1 and ScHKT1;2, as well as a silenced line at both loci from a near isogenic line (NIL14), homozygous for the Solanum cheesmaniae haplotype containing both HKT1 loci and subjected to salinity under natural greenhouse conditions. Our results show that salt treatment reduced vegetative growth and altered the Na+/K+ ratio in leaves and flowers; negatively affecting fruit production, particularly in graft combinations containing single silenced ScHKT1;2- and double silenced ScHKT1;1/ScHKT1;2 lines when used as scion. We concluded that the removal of Na+ from the xylem by ScHKT1;2 in the aerial part of the plant can have an even greater impact than that on Na+ homeostasis at the root level under saline conditions. Also, ScHKT1;1 function loss in rootstock greatly reduced the Na+/K+ ratio in leaf and flower tissues, minimized yield loss under salinity. Our results suggest that, in addition to xylem Na+ unloading, ScHKT1;2 could also be involved in Na+ uploading into the phloem, thus promoting Na+ recirculation from aerial parts to the roots. This recirculation of Na+ to the roots through the phloem could be further favoured by ScHKT1;1 silencing at these roots.Spanish Ministerio de Ciencia e Innovacion/Agencia Estatal de Investigacion AGL2017-82452-C2-1R AGL2017-82452-C2-2RFEDER "Una manera de hacer Europa" MCIN/AEI/10.13039/501100011033University of Granada ACCESP2018JAE Intro-CSIC grant JAEINT_19_0056

Revistas extranjeras

Si rassegnano criticamente gli ultimi sei mesi delle riviste straniere. Il mio contributo si basa sul selezionare criticamente 5-8 contributi nelle riviste di common law, in concreto: Cambridge Law Journal, The Law Quarterly Review, The Modern Law Review, Oxford Journal of Legal Studies, American Journal of Comparative Law, Columbia Law Review, Harvard Law Review, Tulane Law Review, Yale Law Journal, California Law Review

Revistas extranjeras

Si rassegnano criticamente gli ultimi sei mesi delle riviste straniere. Il mio contributo si basa sul selezionare criticamente 5-8 contributi nelle riviste di common law, in concreto: Cambridge Law Journal, The Law Quarterly Review, The Modern Law Review, Oxford Journal of Legal Studies, American Journal of Comparative Law, Columbia Law Review, Harvard Law Review, Tulane Law Review, Yale Law Journal, California Law Review

Revistas extranjeras

Si rassegnano criticamente gli ultimi sei mesi delle riviste straniere. Il mio contributo si basa sul selezionare criticamente 5-8 contributi nelle riviste di common law, in concreto: Cambridge Law Journal, The Law Quarterly Review, The Modern Law Review, Oxford Journal of Legal Studies, American Journal of Comparative Law, Columbia Law Review, Harvard Law Review, Tulane Law Review, Yale Law Journal, California Law Review

Medición de parámetros fisicos, biológicos y químicos en el tramo estuarino del río Ebro

En este artículo se describen las campañas de campo CYTMAR I y II realizadas en la primavera y el verano de 1997, con el fin de estudiar los procesos y los flujos físicos, biológicos y químicos en la zona del Delta del Ebro, tanto en el tramo estuarino del río como en la pluma de agua dulce que se forma en las cercanías de la desembocadura. Aquí el estudio se ha centrado en la zona estuarina, presentando algunos resultados preliminares y analizando las diferencias estacionales observadas

HKT1;1 and HKT1;2 Na+ Transporters from Solanum galapagense Play Different Roles in the Plant Na+ Distribution under Salinity

Salt tolerance is a target trait in plant science and tomato breeding programs. Wild tomato accessions have been often explored for this purpose. Since shoot Na+/K+ is a key component of salt tolerance, RNAi-mediated knockdown isogenic lines obtained for Solanum galapagense alleles encoding both class I Na+ transporters HKT1;1 and HKT1;2 were used to investigate the silencing effects on the Na and K contents of the xylem sap, and source and sink organs of the scion, and their contribution to salt tolerance in all 16 rootstock/scion combinations of non-silenced and silenced lines, under two salinity treatments. The results show that SgHKT1;1 is operating differently from SgHKT1;2 regarding Na circulation in the tomato vascular system under salinity. A model was built to show that using silenced SgHKT1;1 line as rootstock would improve salt tolerance and fruit quality of varieties carrying the wild type SgHKT1;2 allele. Moreover, this increasing effect on both yield and fruit soluble solids content of silencing SgHKT1;1 could explain that a low expressing HKT1;1 variant was fixed in S. lycopersicum during domestication, and the paradox of increasing agronomic salt tolerance through silencing the HKT1;1 allele from S. galapagense, a salt adapted species