title: Expression of genes encoding subunits A and B of succinate dehydrogenase in germinating maize seeds is regulated by methylation of their promoters.
abstract: Succinate dehydrogenase (SDH) activity, isoenzyme pattern, and expression of two genes encoding subunit A and of three genes encoding subunit B have been investigated in the scutellum of germinating maize (Zea mays L.) seeds. Four SDH isoforms were detected electrophoretically and by ion-exchange chromatography at the peak of activity of the glyoxylate cycle (on the 4th and 5th day of germination), while in dry seeds and on the 8th and 9th day of germination only two isoforms were present, which can be related to differential expression of the genes encoding SDH subunits. The levels of transcription of Sdh1-1, Sdh1-2, Sdh2-1, Sdh2-2 and Sdh2-3 and the intensity of methylation of their promoters have been determined. In the course of seed germination, the level of methylation of the promoters of one gene encoding subunit A (Sdh1-1) and of two genes encoding subunit B (Sdh2-1 and Sdh2-2) changed from low to the highest, which resulted in suppression of their transcription during the period when the intensity of the glyoxylate cycle was decreasing, while methylation of the promoter of Sdh2-3 did not change and expression of this gene was constitutive during germination. Methylation of the promoter of Sdh1-2 increased but less sharply as compared to Sdh1-1. It is suggested that epigenetic mechanisms of SDH expression via methylation of promoters play an important role in the regulation of transcription of Sdh1-1, Sdh2-1 and Sdh2-2 in maize seeds during germination. These genes may play a role in the provision of operation of the glyoxylate cycle, while Sdh1-2 and Sdh2-3 are involved mainly in the respiratory processes that are not connected with utilization of succinate formed in the glyoxylate cycle.
authors: Department of Biochemistry and Cell Physiology, Voronezh State University, 394006 Voronezh, Russia.
authors: Alexander T
authors: AT
authors: Eprintsev
authors: Department of Biochemistry and Cell Physiology, Voronezh State University, 394006 Voronezh, Russia.
authors: Dmitry N
authors: DN
authors: Fedorin
authors: Department of Biochemistry and Cell Physiology, Voronezh State University, 394006 Voronezh, Russia.
authors: Lyudmila A
authors: LA
authors: Karabutova
authors: Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada. Electronic address: igamberdiev@mun.ca.
authors: Abir U
authors: AU
authors: Igamberdiev
mesh_terms: D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant; D018525:Germination; D007527:Isoenzymes; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012639:Seeds / Q000201:enzymology / Q000235:genetics; D013385:Succinate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D013385:Succinate Dehydrogenase
keywords: CpG island; Gene expression; Isozymes; Promoter methylation; Succinate dehydrogenase; Zea mays