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Front. Plant Sci. | doi: 10.3389/fpls.2018.00249

Physiological and Metabolic Responses Triggered by Omeprazole Improve Tomato Plant Tolerance to NaCl Stress

  • 1Agricultural Sciences, University of Naples Federico II, Italy
  • 2Università Cattolica del Sacro Cuore, Italy
  • 3Università degli Studi della Campania L. Vanvitelli Naples, Italy
  • 4Agricultural Research Insitute (Cyprus), Cyprus
  • 5Università degli Studi della Tuscia, Italy

Interest in the role of small bioactive molecules (< 500 Da) in plants is on the rise, compelled by plant scientists’ attempt to unravel their mode of action implicated in stimulating growth and enhancing tolerance to environmental stressors. The current study aimed at elucidating the morphological, physiological and metabolomic changes occurring in greenhouse tomato (cv. Seny) treated with omeprazole (OMP), a benzimidazole inhibitor of animal proton pumps. The OMP was applied at three rates (0, 10 or 100 µM) as substrate drench for tomato plants grown under nonsaline (control) or saline conditions sustained by nutrient solutions of 1 or 75 mM NaCl, respectively. Increasing NaCl concentration from 1 to 75 mM decreased the tomato shoot dry weight by 49% in the 0 μM OMP treatment, whereas the reduction was not significant at 10 or 100 µM of OMP. Treatment of salinized (75 mM NaCl) tomato plants with 10 and especially 100 µM OMP decreased Na+ and Cl- while it increased Ca2+ concentration in the leaves. However, OMP was not strictly involved in ion homeostasis since the K+ to Na+ ratio did not increase under combined salinity and OMP treatment. OMP increased root dry weight, root morphological characteristics (total length and surface), transpiration and net photosynthetic rate independently of salinity. Metabolic profiling of leaves through UHPLC liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry facilitated identification of the reprogramming of a wide range of metabolites in response to OMP treatment. Hormonal changes involved an increase in ABA, decrease in auxins and cytokinin, and a tendency for GA down accumulation. Cutin biosynthesis, alteration of membrane lipids and heightened radical scavenging ability related to the accumulation of phenolics and carotenoids were observed. Several other stress-related compounds, such as polyamine conjugates, alkaloids and sesquiterpene lactones, were altered in response to OMP. Although a specific and well-defined mechanism could not be posited, the metabolic processes involved in OMP action suggest that this small bioactive molecule might have a hormone-like activity that ultimately elicits an improved tolerance to NaCl salinity stress.

Keywords: benzimidazole, gas exchange, Hormone-like activity, ion homeostasis, Metabolomics, salt stress, Solanum lycopersicum L.

Received: 25 Jan 2018; Accepted: 12 Feb 2018.

Edited by:

Antonio Ferrante, Università degli Studi di Milano, Italy

Reviewed by:

Georgia Ntatsi, Agricultural University of Athens, Greece
Vincenzo Candido, University of Basilicata, Italy
SPYRIDON A. PETROPOULOS, University of Thessaly, Greece  

Copyright: © 2018 Rouphael, Raimondi, Lucini, Carillo, Kyriacou, Colla, Cirillo, Pannico, El-Nakhel and De Pascale. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Stefania De Pascale, University of Naples Federico II, Agricultural Sciences, Via Università 100, Napoli, 80055, Campania, Italy, depascal@unina.it