Site-Specific Changes in Cytosine Methylation in Promoters of the Genes Encoding the Membrane Subunits of Succinate Dehydrogenase During Germination of Maize Seeds

The cytosine methylation status of symmetric and asymmetric sites of promoters of the genes encoding the membrane-bound subunits C and D of succinate dehydrogenase (SDH) was assessed during the germination of maize (Zea mays L.) seeds, when the stored lipids were utilized and the glyoxylate cycle produced succinate. The results of bisulfite sequencing of the promoters of Sdh genes in maize scutella allowed us to determine the cytosine methylation status in the CG, CNG, and CNN sites. The observed site-specific changes in the cytosine methylation status of the Sdh3-1 and Sdh3-2 genes encoding the SDH subunit C indicate an important role in controlling their transcriptional activity. In contrast, no marked changes were observed in the methylation of promoters of the Sdh4 gene, encoding SDH subunit D. The analysis of changes in the activity of the CG, CNG, and CNN DNA methyltransferases revealed the redistribution of activity between CG, CNG, and CNN DNA methyltransferases toward an increase in the proportion of CG DNA methyltransferases. The locus-specific methylation dynamics of SDH membrane subunit promoters during maize germination have been demonstrated. It is concluded that the changes in the cytosine methylation status may play a role in the regulation of the expression of the Sdh genes in the course of the conversion of succinate formed in the glyoxylate cycle.