title: Compromised telomere maintenance in hypomethylated Arabidopsis thaliana plants.
abstract: Telomeres, nucleoprotein structures at the ends of linear eukaryotic chromosomes, are important for the maintenance of genomic stability. Telomeres were considered as typical heterochromatic regions, but in light of recent results, this view should be reconsidered. Asymmetrically located cytosines in plant telomeric DNA repeats may be substrates for a DNA methyltransferase enzyme and indeed, it was shown that these repeats are methylated. Here, we analyse the methylation of telomeric cytosines and the length of telomeres in Arabidopsis thaliana methylation mutants (met 1-3 and ddm 1-8), and in their wild-type siblings that were germinated in the presence of hypomethylation drugs. Our results show that cytosine methylation in telomeric repeats depends on the activity of MET1 and DDM1 enzymes. Significantly shortened telomeres occur in later generations of methylation mutants as well as in plants germinated in the presence of hypomethylation drugs, and this phenotype is stably transmitted to the next plant generation. A possible role of compromised in vivo telomerase action in the observed telomere shortening is hypothesized based on telomere analysis of hypomethylated telomerase knockout plants. Results are discussed in connection with previous data in this field obtained using different model systems.
authors: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 62500 Brno, Czech Republic, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic and Institute of Biophysics, Academy of Sciences of the Czech Republic v.v.i., Královopolská 135, 612 65 Brno, Czech Republic.
authors: Anna
authors: A
authors: Ogrocká
authors: Pavla
authors: P
authors: Polanská
authors: Eva
authors: E
authors: Majerová
authors: Zlatko
authors: Z
authors: Janeba
authors: Jirí
authors: J
authors: Fajkus
authors: Miloslava
authors: M
authors: Fojtová
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D003596:Cytosine / Q000378:metabolism; D019175:DNA Methylation; D010944:Plants / Q000235:genetics / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000737:chemistry / Q000378:metabolism*; D059505:Telomere Homeostasis; D059506:Telomere Shortening
chemical_list: D003596:Cytosine; D019098:Telomerase