In oil palm (Elaeis guineensis Jacq.), approximately 5% of somatic 
embryo-derived regenerants show homeotic changes during floral development, 
involving an apparent feminization of male parts in flowers of both sexes, 
called the 'mantled' phenotype. This variant phenotype is associated with a 
reduction in the level of global DNA methylation. To explore possible 
relationships between DNA methylation level and accumulation of DNA-(cytosine-5) 
methyltransferase (DNMT) transcripts, the full-length coding sequences 
corresponding to three different DNMT families in oil palm, namely the MET, CMT, 
and DRM classes, have been isolated and characterized. The corresponding genes 
were designated as EgMET1, EgCMT1, and EgDRM1, and encode predicted polypeptides 
of 1543, 925, and 591 amino acid residues, respectively. Expression of oil palm 
DNMTs was compared between normal and variant calli and inflorescence tissues 
using quantitative reverse-transcription PCR. A consistent increase in 
transcript levels of EgMET1 and EgCMT1 was found in variant fast-growing calli 
relative to nodular-compact calli. Nodular-compact calli give rise to about 5% 
of abnormal regenerants whereas fast-growing calli generate 95% of 'mantled' 
palms in their clonal offspring and were previously demonstrated as having 
markedly hypomethylated DNA. In immature abnormal inflorescences only EgMET1 
transcript levels were increased, while no changes in relative abundance of the 
EgCMT1 or EgDRM1 transcripts were observed. Therefore, the genome-wide 
hypomethylation previously described in 'mantled' material cannot be explained 
by a decrease in expression levels of the de novo or maintenance DNMTs, a 
paradox which has been previously reported in tumour cells, where there is 
evidence for global hypomethylation of DNA.