Specific hypomethylation of DNA is induced by heavy metals in white clover and industrial hemp

Abstract

The present study was to assess the effect of heavy metal stress on the DNA methylation of a metal-sensitive plant, Trifolium repens L. and of a metal-tolerant plant, Cannabis sativa L. The changes in the level of 5-methylcytosine (5mC) in the root DNA of plants grown on soils contaminated with different concentrations of Ni 21 , Cd 21 and Cr 61 compared with that of untreated plants, were determined by immunolabelling with a monoclonal antibody, using the Slot-Blot technique. Results showed that DNA of hemp control plants was about three times more methylated than clover DNA, for the same amount of root DNA. Heavy metal treatments induced a global dose-dependent decrease of 5mC content, both in hemp and clover, ranging from 20 to 40%. Changes in methylation pattern of 5 0 -CCGG-3 0 containing sequences were investigated by methylation-sensitive amplification polymorphism (MSAP) technique. Control plants of the same species showed a very similar pattern, suggesting that, in normal condition, methylation involves precise sites. Heavy metals induced DNA methylation changes mainly related to hypomethylation events. These variations were not randomly directed but involved specific DNA sequences, since the detected polymorphisms were the same in all the plants analysed for each treatment.Abbreviations -5mC, 5-methylcytosine; AFLP, amplified fragment length polymorphism; MSAP, methylation-sensitive amplification polymorphism; oxo8dG, 8-oxo-2 0 -deoxyguanosine; ROS, reactive oxygen species.

Is DNA methylation modulated by wounding-induced oxidative burst in maize?

“…However, stress-induced hypomethylation is observed more frequently. It was induced by touching in white bryony (Galaud et al, 1993) and by heavy metals in clover (Aina et al, 2004). When maize seedlings were exposed to cold stress, a genome-wide demethylation occurred in root tissues, but not in leaf blades or stem (Steward et al, 2002).…”

Epigenetics in plant tissue culture

“…Oh et al (2007) hypothesised that labile portions of the genome are affected by stress during micropropagation of Musa. Alterations in methylation have been reported in response to water deficiency (Labra et al 2002), osmotic stress (Kovařik et al 1997), heavy metals (Aina et al 2004), and-in tissue culture-heat (Baránek et al 2010). Some loci acquired epigenetic silencing, while sometimes silenced loci increased expression.…”

Analysis of DNA methylation of perennial ryegrass under drought using the methylation-sensitive amplification polymorphism (MSAP) technique

“…Salt stress elevated the demethylation of genomic DNA in tobacco (Choi and Sano 2007). Under metal stresses, specific hypomethylation of DNA was induced in white clover (Trifolium repens) and industrial hemp (Aina et al 2004). In Sorghum bicolor, DNA methylation alterations have been shown to be associated with aluminum toxicity and low pH (Kimatu et al 2011).…”