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Front. Plant Sci. | doi: 10.3389/fpls.2018.00204

Transcriptome and cell physiological analyses in different rice cultivars provide novel insights into adaptive and salinity stress responses

  • 1Department of Biology, University of Padova, Italy
  • 2Fondazione Edmund Mach, Italy
  • 3Istituto di Biologia e Biotecnologia Agraria (CNR), Italy
  • 4Department of Molecular Medicine, Università degli Studi di Padova, Italy
  • 5Department of Agronomy, Food, Natural Resources, Animal and Environment, DAFNAE, Università degli Studi di Padova, Italy
  • 6Department of Agricultural and Environmental Sciences - Production, Landscape, Agroenergy, Università degli Studi di Milano, Italy

Salinity tolerance is a trait investigated deeply in recent years for its agricultural importance. Several features as regulation of ionic transporters and metabolic adjustments have been identified as salt tolerance hallmarks. Nevertheless, due to the complexity of the trait, the results achieved so far have met with limited success in improving the salt tolerance of rice plants when tested in the field, suggesting that a deeper understanding of the tolerance mechanisms is still required. In this work, differences between two varieties of rice with contrasting salt sensitivity were unveiled by the imaging photosynthetic parameters, ion content analysis and a transcriptomic approach. The transcriptomic analysis conducted on tolerant plants supported the setting up of an adaptive program consisting of the sodium distribution preferentially limited to the roots and older leaves, and in the activation of regulatory mechanisms of photosynthesis in the new leaves. As a result, plants resumed growth even under prolonged saline stress. In contrast, in the sensitive variety, RNA-seq analysis revealed a misleading response, ending into senescence and cell death. The physiological response at the cellular level was investigated by measuring the intracellular profile of H2O2 in the roots, using a fluorescent probe. In the roots of tolerant plants, a quick response was observed with an increase in H2O2 production in 5 minutes after salt treatment. The expression analysis of some of the genes involved in perception, signal transduction and salt stress response confirmed their early induction in roots of tolerant plants compared to sensitive ones. By inhibiting the synthesis of the apoplastic H2O2, a reduction in the expression of these genes was detected. Our results indicate that a quick H2O2 signalling in the roots participates in a coordinated response that leads to adaptation instead of senescence in salt-treated rice plants.

Keywords: Oryza sativa (rice), salt stress, RNA sequencing, ion transporters, H2O2, Salt tolerance mechanisms

Received: 28 Jul 2017; Accepted: 02 Feb 2018.

Edited by:

Sonia Negrao, King Abdullah University of Science and Technology, Saudi Arabia

Reviewed by:

Mirza Hasanuzzaman, Sher-e-Bangla Agricultural University, Bangladesh
Baris Uzilday, Ege University, Turkey
Camilla B. Hill, Murdoch University, Australia  

Copyright: © 2018 Formentin, Sudiro, Perin, Riccadonna, Barizza, Baldoni, Lavezzo, Stevanato, Sacchi, Fontana, Toppo, Morosinotto, Zottini and Lo Schiavo. 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: Dr. Elide Formentin, University of Padova, Department of Biology, Padova, Italy, elide.formentin@gmail.com