Salt tolerant and sensitive rice varieties display differential methylome flexibility under salt stress

摘要

DNA methylation has been referred as an important player in plant genomic responses toenvironmental stresses but correlations between the methylome plasticity and specific traitsof interest are still far from being understood. In this study, we inspected global DNA methylationlevels in salt tolerant and sensitive rice varieties upon salt stress imposition. GlobalDNA methylation was quantified using the 5-methylcytosine (5mC) antibody and an ELISAbasedtechnique, which is an affordable and quite pioneer assay in plants, and in situ imagingof methylation sites in interphase nuclei of tissue sections. Variations of global DNAmethylation levels in response to salt stress were tissue- and genotype-dependent. Weshow a connection between a higher ability of DNA methylation adjustment levels and saltstress tolerance. The salt-tolerant rice variety Pokkali was remarkable in its ability to quicklyrelax DNA methylation in response to salt stress. In spite of the same tendency for reductionof global methylation under salinity, in the salt-sensitive rice variety IR29 such reductionwas not statistically supported. In ‘Pokkali’, the salt stress-induced demethylation may belinked to active demethylation due to increased expression of DNA demethylases undersalt stress. In ‘IR29’, the induction of both DNA demethylases and methyltransferases mayexplain the lower plasticity of DNA methylation. We further show that mutations for epigeneticregulators affected specific phenotypic parameters related to salinity tolerance, suchas the root length and biomass. This work emphasizes the role of differential methylomeflexibility between salt tolerant and salt sensitive rice varieties as an important player in saltstress tolerance, reinforcing the need to better understand the connection between epigeneticnetworks and plant responses to environmental stresses.