Effect of anti-DNA methylation drugs on growth, level of methylated DNA, peroxidase activity and ethylene production of Bryonia dioica internodes

A previous paper (Galaud et al. 1993. Physiol. Plant. 87: 25–30) reported a rapid demethylation of DNA after mechanical rubbing of young Bryonia dioica internodes, leading to growth inhibition. In order to assess an eventual causative role of DNA demethylation in the mechanisms underlying thigmomorphogenesis, the effects of the anti-DNA methylation drugs, 5-azacytosine (5-azacyt) and 5-azacytidine (5-azacyd) were investigated. Treatment with 5-azacyd induced a decrease of the methylated DNA level. This was accompanied by an increase of peroxidase activity and of ethylene production. On the contrary, 5-azacyt had no significant effect on growth, peroxidase activity and ethylene production. The use of 5-azacyd as an inducer of DNA demethylation is discussed in relation to the control of gene expression