The DNA methylation level against the background of the genome size and t-heterochromatin content in some species of the genusSecale L

Abstract

Methylation of cytosine in DNA is one of the most important epigenetic modifications in eukaryotes and plays a crucial role in the regulation of gene activity and the maintenance of genomic integrity. DNA methylation and other epigenetic mechanisms affect the development, differentiation or the response of plants to biotic and abiotic stress. This study compared the level of methylation of cytosines on a global (ELISA) and genomic scale (MSAP) between the species of the genusSecale. We analyzed whether the interspecific variation of cytosine methylation was associated with the size of the genome (C-value) and the content of telomeric heterochromatin. MSAP analysis showed thatS. sylvestrewas the most distinct species among the studied rye taxa; however, the results clearly indicated that these differences were not statistically significant. The total methylation level of the studied loci was very similar in all taxa and ranged from 60% inS. strictumssp.africanumto 66% inS. cerealessp.segetale, which confirmed the lack of significant differences in the sequence methylation pattern between the pairs of rye taxa. The level of global cytosine methylation in the DNA was not significantly associated with the content of t-heterochromatin and did not overlap with the existing taxonomic rye relationships. The highest content of 5-methylcytosine was found inS. cerealessp.segetale(83%), while very low inS. strictumssp.strictum(53%), which was significantly different from the methylation state of all taxa, except forS. sylvestre. The other studied taxa of rye had a similar level of methylated cytosine ranging from 66.42% (S. vavilovii) to 74.41% in (S. cerealessp.afghanicum). The results obtained in this study are evidence that the percentage of methylated cytosine cannot be inferred solely based on the genome size or t-heterochromatin. This is a significantly more complex issue.