Hypomethylation of CNG targets induced with dihydroxypropyladenine is rapidly reversed in the course of mitotic cell division in tobacco

Koukalová, B.; Votruba, Ivan; Fojtová, Miloslava; Holý, Antonı́n; Kovařı́k, Aleš

doi:10.1007/s00122-002-0965-6

Cited by 6 publications

(2 citation statements)

References 36 publications

(36 reference statements)

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“…In leaves of wt plants segregated from the met1-3 mutant background, the methylation was almost comparable to samples without a mutant history, although in some individuals bands evidencing the non-methylated cytosines in the CCGG sequence motif were visible (Supplementary Figure S1A). In mature leaves of DHPA-treated plants that were grown in soil without the drugs, methylation returned to control levels (Supplementary Figure S1B), consistent with the transient hypomethylation effect described for this drug (44). Variable patterns of centromeric repeat methylations were observed in plants germinated in the presence of ZEB and even in the progenies of plants affected by 250 µM ZEB, although in these cases, the levels of non-methylated cytosines in CCGG sequences were significantly lower than those in ZEB-treated seedlings (Supplementary Figure S1B).…”

Section: Resultssupporting

confidence: 79%

“…during the developmental stage when plant tissue is in direct contact with the drug (Figure 2; Supplementary Figure S1B). During cultivation of plants in soil without drugs, DHPA-induced hypomethylation was completely reversed (Figure 2; Supplementary Figure S1B), as was observed in previous experiments using tobacco plants and cell cultures (44,45). Although the hypomethylating effect of ZEB was also reported as transient (41), in our experiments, distinct hypomethylation of cytosines located in CCGG sequences was detectable even in the next plant generation (Supplementary Figure S1B).…”

Section: Discussionsupporting

confidence: 79%

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Compromised telomere maintenance in hypomethylated Arabidopsis thaliana plants

Ogrocká¹,

Polanská²,

Majerová³

et al. 2013

Nucleic Acids Research

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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.

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Section: Resultssupporting

confidence: 79%

Section: Discussionsupporting

confidence: 79%

Compromised telomere maintenance in hypomethylated Arabidopsis thaliana plants

Ogrocká¹,

Polanská²,

Majerová³

et al. 2013

Nucleic Acids Research

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Down-regulation of S-adenosyl-l-homocysteine hydrolase reveals a role of cytokinin in promoting transmethylation reactions

Jiang

et al. 2008

Planta

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S-adenosyl-L: -homocysteine hydrolase (SAHH) is a key enzyme for maintenance of cellular transmethylation potential. Although a cytokinin-binding activity had been hypothesized for SAHH, the relation between cytokinin and transmethylation reactions has not been elucidated. Here we show that, of the two Arabidopsis thaliana SAHH genes, AtSAHH1 has a much higher expression level than AtSAHH2. A T-DNA insertion mutant of AtSAHH1 (sahh1-1) and the RNA interference (RNAi) plants (dsAtSAHH2) accumulated a higher level of cytokinins, exhibited phenotypic changes similar to those of cytokinin-overproducers, and their global DNA methylation status was reduced. On the other hand, cytokinins positively regulate the transmethylation pathway genes, including AtSAHH1, AtADK1 (for adenosine kinase), and this regulation involves the cytokinin activity. Furthermore, expression of three cytosine DNA methyltransferase genes examined was inducible by cytokinin treatment. Unlike adenine and adenosine which are SAHH inhibitors, the adenine-type cytokinins have no effect on SAHH activity at protein level. Changing of endogenous cytokinin levels by transgene expression resulted in alterations of DNA methylation status in the sahh1-1 background, suggesting that cytokinins promote DNA methylation, at least under transmethylation stringent conditions. These data demonstrate that the phytohormone cytokinin plays a role in promoting transmethylation reactions, including DNA methylation.

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Inhibition of SAH-hydrolase activity during seed germination leads to deregulation of flowering genes and altered flower morphology in tobacco

et al. 2011

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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.

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Hypomethylation of CNG targets induced with dihydroxypropyladenine is rapidly reversed in the course of mitotic cell division in tobacco

Cited by 6 publications

References 36 publications

Compromised telomere maintenance in hypomethylated Arabidopsis thaliana plants

Compromised telomere maintenance in hypomethylated Arabidopsis thaliana plants

Down-regulation of S-adenosyl-l-homocysteine hydrolase reveals a role of cytokinin in promoting transmethylation reactions

Inhibition of SAH-hydrolase activity during seed germination leads to deregulation of flowering genes and altered flower morphology in tobacco

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