Epigenetics deals with changes in gene expression that are not caused by modifications in the primary sequence of nucleic acids. These changes beyond primary structures of nucleic acids not only include DNA/RNA methylation, but also other reversible conversions, together with histone modifications or RNA interference. In addition, under particular conditions (such as specific ion concentrations or protein-induced stabilization), the right-handed double-stranded DNA helix (B-DNA) can form noncanonical structures commonly described as "non-B DNA" structures. These structures comprise, for example, cruciforms, i-motifs, triplexes, and G-quadruplexes. Their formation often leads to significant differences in replication and transcription rates. Noncanonical RNA structures have also been documented to play important roles in translation regulation and the biology of noncoding RNAs. In human and animal studies, the frequency and dynamics of noncanonical DNA and RNA structures are intensively investigated, especially in the field of cancer research and neurodegenerative diseases. In contrast, noncanonical DNA and RNA structures in plants have been on the fringes of interest for a long time and only a few studies deal with their formation, regulation, and physiological importance for plant stress responses. Herein, we present a review focused on the main fields of epigenetics in plants and their possible roles in stress responses and signaling, with special attention dedicated to noncanonical DNA and RNA structures.

• Klíčová slova
• Acetylation, Chromatin, Epigenetics, G-quadruplex, Gene expression, Histone, Methylation, Non-B DNA, Stress signaling,
• MeSH
• DNA genetika   chemie   MeSH
• epigeneze genetická MeSH
• G-kvadruplexy * MeSH
• lidé MeSH
• nukleové kyseliny * MeSH
• RNA genetika   chemie   MeSH
• rostliny genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA MeSH
• nukleové kyseliny * MeSH
• RNA MeSH

Increasing evidence for epigenetic variation within and among natural plant populations has led to much speculation about its role in the evolution of plant phenotypes. However, we still have a very limited understanding of the evolutionary potential of epigenetic variation, in particular in comparison to DNA sequence-based variation. To address this question, we compared the magnitudes of heritable phenotypic variation in epigenetic recombinant inbred lines (epiRILs) of Arabidopsis thaliana-lines that mainly differ in DNA methylation but only very little in DNA sequence-with other types of A. thaliana lines that differ strongly also in DNA sequence. We grew subsets of two epiRIL populations with subsets of two genetic RIL populations, of natural ecotype collections, and of lines from a natural population in a common environment and assessed their heritable variation in growth, phenology, and fitness. Among-line phenotypic variation and broad-sense heritabilities tended to be largest in natural ecotypes, but for some traits the variation among epiRILs was comparable to that among RILs and natural ecotypes. Within-line phenotypic variation was generally similar in epiRILs, RILs, and ecotypes. Provided that phenotypic variation in epiRILs is mainly caused by epigenetic differences, whereas in RILs and natural lines it is largely driven by sequence variation, our results indicate that epigenetic variation has the potential to create phenotypic variation that is stable and substantial, and thus of evolutionary significance.

• MeSH
• Arabidopsis genetika   fyziologie   MeSH
• biologická evoluce * MeSH
• biologická variabilita populace MeSH
• DNA rostlinná MeSH
• ekotyp * MeSH
• epigeneze genetická * MeSH
• genetická variace * MeSH
• kvantitativní znak dědičný * MeSH
• metylace DNA MeSH
• populační genetika * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH

Developmental processes are closely connected to certain states of epigenetic information which, among others, rely on methylation of chromatin. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are key cofactors of enzymes catalyzing DNA and histone methylation. To study the consequences of altered SAH/SAM levels on plant development we applied 9-(S)-(2,3-dihydroxypropyl)-adenine (DHPA), an inhibitor of SAH-hydrolase, on tobacco seeds during a short phase of germination period (6 days). The transient drug treatment induced: (1) dosage-dependent global DNA hypomethylation mitotically transmitted to adult plants; (2) pleiotropic developmental defects including decreased apical dominance, altered leaf and flower symmetry, flower whorl malformations and reduced fertility; (3) dramatic upregulation of floral organ identity genes NTDEF, NTGLO and NAG1 in leaves. We conclude that temporal SAH-hydrolase inhibition deregulated floral genes expression probably via chromatin methylation changes. The data further show that plants might be particularly sensitive to accurate setting of SAH/SAM levels during critical developmental periods.

• MeSH
• adenin analogy a deriváty   toxicita   MeSH
• adenosylhomocysteinasa antagonisté a inhibitory   metabolismus   MeSH
• DNA primery genetika   MeSH
• epigeneze genetická účinky léků   fyziologie   MeSH
• klíčení účinky léků   fyziologie   MeSH
• komplementární DNA genetika   MeSH
• květy anatomie a histologie   fyziologie   MeSH
• metylace DNA MeSH
• neparametrická statistika MeSH
• pyl fyziologie   MeSH
• regulace genové exprese u rostlin účinky léků   genetika   fyziologie   MeSH
• rostlinné proteiny metabolismus   MeSH
• Southernův blotting MeSH
• tabák enzymologie   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• adenosylhomocysteinasa MeSH
• DNA primery MeSH
• GLO protein, Nicotiana tabacum MeSH Prohlížeč
• komplementární DNA MeSH
• rostlinné proteiny MeSH

The widespread occurrence of epigenetic alterations in allopolyploid species deserves scrutiny that DNA methylation systems may be perturbed by interspecies hybridization and polyploidization. Here we studied the genes involved in DNA methylation in Nicotiana tabacum (tobacco) allotetraploid containing S and T genomes inherited from Nicotiana sylvestris and Nicotiana tomentosiformis progenitors. To determine the inheritance of DNA methyltransferase genes and their expression patterns we examined three major DNA methyltransferase families (MET1, CMT3 and DRM) from tobacco and the progenitor species. Using Southern blot hybridization and PCR-based methods (genomic CAPS), we found that the parental loci of these gene families are retained in tobacco. Homoeologous expression was found in all tissues examined (leaf, root, flower) suggesting that DNA methyltransferase genes were probably not themselves targets of uniparental epigenetic silencing for over thousands of generations of allotetraploid evolution. The level of CG and CHG methylation of selected high-copy repeated sequences was similar and high in tobacco and its diploid progenitors. We speculate that natural selection might favor additive expression of parental DNA methyltransferase genes maintaining high levels of DNA methylation in tobacco, which has a repeat-rich heterochromatic genome.

• MeSH
• diploidie MeSH
• DNA rostlinná genetika   MeSH
• DNA-(cytosin-5-)methyltransferasa klasifikace   genetika   metabolismus   MeSH
• epigeneze genetická MeSH
• exprese genu MeSH
• fylogeneze MeSH
• genom rostlinný MeSH
• klonování DNA MeSH
• metylace DNA genetika   MeSH
• molekulární sekvence - údaje MeSH
• multigenová rodina * MeSH
• polyploidie MeSH
• repetitivní sekvence nukleových kyselin MeSH
• rostlinné geny * MeSH
• sekvence nukleotidů MeSH
• selekce (genetika) MeSH
• tabák enzymologie   genetika   MeSH
• tkáňová distribuce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH
• DNA-(cytosin-5-)methyltransferasa MeSH

Epigenetic changes accompanying plant cell dedifferentiation and differentiation are reported in 35S ribosomal DNA (rDNA) of tobacco (Nicotiana tabacum). There was a reduction of CG and CNG methylation in both intergenic and genic regions of the rDNA cistron in fully dedifferentiated callus and root compared to leaf. The rDNA hypomethylation was not random, but targeted to particular rDNA gene families at units that are clustered within the tandem array. The process of hypomethylation was initiated as early as 2 weeks after the callus induction and established epigenetic patterns were stably maintained throughout prolonged culture. However, regenerated plants and their progeny showed partial and complete remethylation of units, respectively. Nuclear run-on assays revealed a 2-fold increase of primary (unprocessed) ribosomal RNA transcripts in callus compared to leaf tissue. However, the abundance of mature transcripts in callus was elevated by only about 25%. Fluorescence in situ hybridization analysis of interphase nuclei showed high levels of rDNA chromatin condensation in both callus and leaf, with substantially less decondensed rDNA than is observed in meristematic root-tip cells. It is likely that the regions of the rDNA locus showing decondensation correspond to the clusters of hypomethylated units that occur in the tandem array at each locus. The data together indicate that the establishment of pluripotency and cell proliferation occurring with callus induction is associated with enhanced ribosomal RNA gene expression and overall rDNA hypomethylation, but is not associated with material-enhanced relaxation of chromatin structure (decondensation) at rDNA loci.

• MeSH
• buněčná diferenciace * MeSH
• chromatin chemie   metabolismus   MeSH
• genetická transkripce genetika   MeSH
• hybridizace in situ fluorescenční MeSH
• interfáze MeSH
• kořeny rostlin genetika   MeSH
• kultivované buňky MeSH
• listy rostlin cytologie   genetika   MeSH
• messenger RNA genetika   metabolismus   MeSH
• metylace DNA * MeSH
• regenerace MeSH
• regulace genové exprese u rostlin MeSH
• RNA ribozomální genetika   MeSH
• tabák cytologie   genetika   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromatin MeSH
• messenger RNA MeSH
• RNA ribozomální MeSH