Improved yield, fruit quality, and salt resistance in tomato co-overexpressing LeNHX2 and SlSOS2 genes

The K, Na/H antiporter LeNHX2 and the regulatory kinase SlSOS2 are important determinants of salt tolerance in tomato plants and their fruit production ability. In this work, we have analyzed the effects of LeNHX2 and SlSOS2 co-overexpression on fruit production, quality in tomato plants (Solanum lycopersicum L. cv. MicroTom), and analyzed physiological parameters related to salt tolerance. Plants overexpressing LeNHX2, SlSOS2 or both were grown in greenhouse. They were treated with 125 mM NaCl or left untreated and their salt tolerance was analyzed in terms of plant biomass and fruit yield. Under NaCl cultivation conditions, transgenic tomato plants overexpressing either SlSOS2 or LeNHX2 or both grew better and showed a higher biomass compared to their wild-type plants. Proline, glucose and protein content in leaves as well as pH and total soluble solid (TSS) in fruits were analyzed. Our results indicate that salinity tolerance of transgenic lines is associated with an increased proline, glucose and protein content in leaves of plants grown either with or without NaCl. Salt treatment significantly reduced yield, pH and TSS in fruits of WT plants but increased yield, pH and TSS in fruits of transgenic plants, especially those overexpressing both LeNHX2 and SlSOS2. All these results indicate that the co-overexpression of LeNHX2 and SlSOS2 improve yield and fruit quality of tomato grown under saline conditions.This work was supported by grants from National Centre for Scientific and Technical Research-CNRST and Minister for Higher Education, Scientific Research and Executive Training— Morocco (PPR/2015/21). Consejería de Economía, Innovación Ciencia y Empresa, Junta de Andalucía, Spain (CVI-7558 to MPRR), Spanish Ministry of Economy and Competitiveness and Agencia Estatal de Investigación (BIO2015-65056-P, BIO2016-81957-REDT/ AEI and Programa I-COOPB + 2013 Ref: COOPB20053)

Gibberellic acid and indole acetic acid improves salt tolerance in transgenic tomato plants overexpressing LeNHX4 antiporter

Salinity is the major environmental factor that limits plant growth and productivity. High concentrations of Na and Cl ions in soil solution negatively affect K uptake and may cause physiological and metabolic disorders, which adversely affect the plant growth and crop yield. In plants, NHX antiporters play an important role in salt tolerance by catalyzing Na accumulation in vacuoles. In this work, we studied the effect of exogenous plants hormones auxin (IAA) and gibberellic acid (GA), on salinity tolerance, fruit production and quality in transgenic tomato plants overexpressing LeNHX4 antiporter grown under 125 mM NaCl. Here, we have found that IAA and GA positively affected leaf proline, glucose, soluble proteins and ortho-diphenol. In addition, both hormones increased tomato production and fruit quality parameters. These results suggest that GA and IAA improved salinity tolerance and increased fruit yield and quality, probably by increasing the expression or the activity of LeNHX4 antiporter.This work was supported by grants from National Centre for Scientific and Technical Research and Minister for Higher Education, Scientific Research and Executive Training (Morocco) Ref: PPR/2015/21. CSIC Progamme for scientific cooperation for development (I-COOP-B + 2013; Ref: COOPB20053

Overexpression of LeNHX2 and SlSOS2 increases salt tolerance and fruit production in double transgenic tomato plants

Transgenic tomato plants (Solanum lycopersicum L. cv. MicroTom) overexpressing both the K,Na/H antiporter LeNHX2 and the regulatory kinase SlSOS2 were produced by crossing transgenic homozygous lines overexpressing LeNHX2 and SlSOS2. LeNHX2 expression was enhanced in plants overexpressing LeNHX2 but surprisingly even more in plants overexpressing SlSOS2 with and without LeNHX2. All transgenic plants showed better NaCl tolerance than wild type controls and plants overexpressing both LeNHX2 and SlSOS2 grew better under saline conditions than plants overexpressing only one of these genes. Yield related parameters indicated that single and above all double transgenic plants performed significantly better than wild type controls. All transgenic plants produced fruits with a higher K content than wild-type plants and plants overexpressing SlSOS2 accumulated more Na in fruits than the rest of the plants when grown with NaCl. Roots, stems and leaves of transgenic plants overexpressing LeNHX2 showed a higher K content than wild type and single transgenic plants overexpressing SlSOS2. Na content in stems and leaves of NaCl treated plants was higher in SlSOS2 overexpressing plants than in wild type and LeNHX2 single transgenic plants. All transgenic lines showed a higher leaf relative water content and a higher plant water content and water use efficiency than wild type controls when both were grown in the presence of NaCl. Results in this work indicate that the joint overexpression of LeNHX2 and SlSOS2 improves growth and water status under NaCl stress, affects K and Na homeostasis and enhances fruit yield of tomato plants.This work was supported by grants from Consejería de Economía, Innovación, Ciencia y Empresa, Junta de Andalucía, Spain (CVI-7558 to MPRR), Spanish MINECO and Agencia Estatal de Investigación (BIO2015-65056-P and BIO2016-81957-REDT/AEI to KV and MPRR) and Moroccan MESRSFC and CNRST (PPR/2015/21 to MB).Peer Reviewe

Overexpression of LeNHX4 improved yield, fruit quality and salt tolerance in tomato plants (Solanum lycopersicum L.)

The function of the tomato K, Na/H antiporter LeNHX4 has been analyzed using 35S-driven gene construct for overexpressing a histagged LeNHX4 protein in Solanum lycopersicum L. Compared to wild-type plants, the expression of LeNHX4 was enhanced in most of plants transformed with a gene construct for LeNHX4 overexpression although some plants showed a decreased LeNHX4 expression. Overexpression of LeNHX4 was associated to an increased fruit size while silencing of this gene was related to a decreased fruit size. We have investigated the effect of LeNHX4 overexpression on fruit production and quality and we have also evaluated salt tolerance in two different overexpression lines by measuring proline, protein and glucose concentrations in tomato leaves grown either under control (0 mM NaCl) or saline (125 mM NaCl) conditions. Plants overexpressing LeNHX4 showed a higher amount of fruits than WT plants and accumulated higher contents of sugars and cations (Na and K). The application of 125 mM NaCl, affected negatively fruit production and quality of WT plants. However the transgenic lines overexpressing LeNXH4 increased fruit quality and yield. In relation to salt tolerance, overexpression lines showed higher levels of leaf proline, glucose and proteins under NaCl treatment. The overexpression of LeNHX4 in tomato plants, improved salinity tolerance and increased fruit yield and quality under both normal and salinity stress conditions.This work was supported by Grants from Consejería de Economía, Innovación, Ciencia y Empresa, Junta de Andalucía, Spain (CVI-7558 to MPRR), Spanish Ministry of Economy and Competitiveness and Agencia Estatal de Investigación (BIO2015-65056-P, BIO2016-81957-REDT/AEI and Programa I-COOPB+2013 Ref. COOPB20053 National Centre for Scientific and Technical Research COOPB20053). and Minister for Higher Education, Scientific Research and Executive Training (Morocco)