Salt Tolerant and Sensitive Rice Varieties Display Differential Methylome Flexibility under Salt Stress

PLoS One. 2015 May 1;10(5):e0124060. doi: 10.1371/journal.pone.0124060. eCollection 2015.

Abstract

DNA methylation has been referred as an important player in plant genomic responses to environmental stresses but correlations between the methylome plasticity and specific traits of interest are still far from being understood. In this study, we inspected global DNA methylation levels in salt tolerant and sensitive rice varieties upon salt stress imposition. Global DNA methylation was quantified using the 5-methylcytosine (5mC) antibody and an ELISA-based technique, which is an affordable and quite pioneer assay in plants, and in situ imaging of methylation sites in interphase nuclei of tissue sections. Variations of global DNA methylation levels in response to salt stress were tissue- and genotype-dependent. We show a connection between a higher ability of DNA methylation adjustment levels and salt stress tolerance. The salt-tolerant rice variety Pokkali was remarkable in its ability to quickly relax DNA methylation in response to salt stress. In spite of the same tendency for reduction of global methylation under salinity, in the salt-sensitive rice variety IR29 such reduction was not statistically supported. In 'Pokkali', the salt stress-induced demethylation may be linked to active demethylation due to increased expression of DNA demethylases under salt stress. In 'IR29', the induction of both DNA demethylases and methyltransferases may explain the lower plasticity of DNA methylation. We further show that mutations for epigenetic regulators affected specific phenotypic parameters related to salinity tolerance, such as the root length and biomass. This work emphasizes the role of differential methylome flexibility between salt tolerant and salt sensitive rice varieties as an important player in salt stress tolerance, reinforcing the need to better understand the connection between epigenetic networks and plant responses to environmental stresses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • DNA Methylation / drug effects
  • DNA Methylation / genetics*
  • Epigenesis, Genetic / drug effects
  • Gene Expression Regulation, Plant / drug effects
  • Genotype
  • Histone Demethylases / metabolism
  • Imaging, Three-Dimensional
  • Interphase / drug effects
  • Metabolome / genetics*
  • Methyltransferases / metabolism
  • Mutation / genetics
  • Oryza / drug effects
  • Oryza / genetics*
  • Oryza / physiology*
  • Phenotype
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Salt Tolerance / drug effects
  • Salt Tolerance / genetics*
  • Sodium Chloride / pharmacology
  • Stress, Physiological / drug effects*
  • Stress, Physiological / genetics

Substances

  • Plant Proteins
  • Sodium Chloride
  • Histone Demethylases
  • Methyltransferases

Grants and funding

The work was funded by Portuguese Foundation for Science and Technology (FCT) through the project "Epigenetic regulation of the rice genome under environmental stresses- BIA/BCM/111645/2009". APS and LF were financially supported by the following FCT grants: BPD/74197/2010 e BD/61428/2009, respectively. Research unit GREEN-it "Bioresources for Sustainability" (UID/Multi/04551/2013). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.