Heterogeneity of Pumpkin Ribosomal DNA

Siegel, Albert; Kolacz, Kathryn

doi:10.1104/pp.72.1.166

Cited by 45 publications

(21 citation statements)

References 27 publications

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“…Similar conclusions are derived for the two types of sequences. Variable base modification on rDNA has also been shown for pumpkin (27) (26), this would indicate that the different units are not equivalent with respect to transcription.…”

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confidence: 95%

“…It is therefore relevant to investigate the methylation pattern of specific plant genes and compare it with the animal situation. Preliminary observations have suggested that plant rDNA is almost completely methylated at Hpa II sites (15,27,30) and more detailed studies have revealed a complex methylation pattern for flax 5S rRNA genes (17) and for a satellite DNA sequences from Scilla (12). A recent study dealing with flax rDNA has established that some specific Hpa II sites are hypomethylated (14).…”

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confidence: 99%

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Methylation Pattern of Radish (Raphanus sativus) Nuclear Ribosomal RNA Genes

Delseny¹,

Laroche²,

Penon³

1984

Plant Physiol.

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The methylation pattern of radish Raphanus sativus nuclear rDNA has been investigated using the Hpa II, Msp I, and Hha I restriction enzymes. The presence of numerous target sites for these enzymes has been shown using cloned rDNA fragments. A large fraction of the numerous rDNA units are heavily methylated, being completely resistant to Hpa II and Hpa I. However, specific sites are constantly available in another fraction of the units and are therefore unmethylated. Although site-specific methylation of eukaryotic DNA is considered to play a key role in gene regulation (13,26,31), there is so far very little information concerning higher plant genes. It has been known for a long time that higher plant DNA has a much higher 5-methylcytosine level than animal DNA (29), and plant DNA is usually considered to be heavily methylated (18,19 (Fig. 1). This fragment spans the 3' moiety of the 18S r RNA sequences, the internal transcribed spacer, and the 5' part of the 25S rRNA sequence (11). Bacteriophage A RA 2 results from the cloning of Eco RI partial digests of radish DNA into A gt WES/A B vector (22).

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Methylation Pattern of Radish (Raphanus sativus) Nuclear Ribosomal RNA Genes

Delseny¹,

Laroche²,

Penon³

1984

Plant Physiol.

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“…Lilium rDNA, like that of many other plants (4,5,6,7,18,19,22) is heavily methylated. Only two sites were detected using 10 restriction enzymes whose six-base recognition sites contain methylatable CG or CNG, whereas 17 sites were mapped with 10 other enzymes lacking such CG or CNG sequences (Fig.…”

Section: Discussionmentioning

confidence: 99%

An under-methylated region in the spacer of ribosomal RNA genes of Lilium henryi

1986

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Ribosomal RNA genes of Lilium henryi are almost completely methylated at CG and CNG sequences. A short under-methylated region was detected between 2.05 and 2.4 kbp upstream of the 18S sequences. It included the only sites of digestion by four methylation-sensitive restriction endonucleases - PstI, Hae II, Eco RII and Hpa II. Only about 15%-20% of rDNA repeats from shoot meristem are susceptible to each of the enzymes. The same repeats are apparently cut by all enzymes and occur in contiguous blocks. Because the region involved is likely to include regulatory sequences it may be that under-methylation occurs specifically in active rDNA repeats. To test this, rDNA was examined from pollen mother cells at pachytene where transcription has fallen to near zero. Under-methylation levels here were similar to those in shoot meristem tissue. Thus methylation of this region is not the agent responsible for rDNA gene inactivation in pachytene cells and it does not occur immediately genes become inactive. Even so, sequences in this region might be prevented from becoming methylated in transcribing repeats.

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“…Among repeat units, a limited amount of restriction site polymorphism in the large spacer, due to either nucleotide mutations or methylation, was occasionally seen. This variation was evident in digests using BamH I and Bgl I-restriction enzymes that recognize sequences prone to methylation (Gerlach and Bedbrook, 1979;Siegel and Kolacz, 1983). This lack of extensive rDNA variation within and among individuals in Lisianthius populations thus permits a straightforward phylogenetic analysis of rDNA heterogeneity among populations and species.…”

Section: Ribosomal Dna Variationmentioning

confidence: 99%

PHYLOGENETICS OF THE LISIANTHIUS SKINNERI (GENTIANACEAE) SPECIES COMPLEX IN PANAMA UTILIZING DNA RESTRICTION FRAGMENT ANALYSIS

1985

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Abstract.-The well-delimited and evolutionary interesting tropical shrub group, the Lisianthius skinneri (Gentianaceae) species complex, was analyzed for variation in nuclear ribosomal DNA and chloroplast DNA by restriction endonuclease fragment analysis. A most parsimonious tree using variations in both DNAs was constructed for seven populations in the group by including an appropriate outgroup, This phylogeny is significantly more compatible with the DNA data than most, but not all, less parsimonious phylogenies. At least two distinct lineages have independently evolved geographically restricted, cloud forest species from the putative ancestral, widespread, and lower elevation L. skinneri. Lisianthius skinneri itselfis shown to be paraphyletic with populations derived separately from the two distinct lineages. Except for a switch in the placement of two populations, this DNA-based phylogeny is congruent with an isozyme-based Wagner network depicting relationships in the species complex. Relative rates of divergence, in terms of nuclear ribosomal DNA, chloroplast DNA, isozymes, and morphology, differ markedly within and between lineages. The non-transcribed spacer region of ribosomal DNA is shown to evolve in a manner that is not in accord with a molecular clock hypothesis. Small population sizes, restricted and isolated nature of populations, and probable founder events are suggested as instrumental in causing this lack of concerted divergence within and between lineages of the L. skinneri species complex.

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Heterogeneity of Pumpkin Ribosomal DNA

Cited by 45 publications

References 27 publications

Methylation Pattern of Radish (Raphanus sativus) Nuclear Ribosomal RNA Genes

Methylation Pattern of Radish (Raphanus sativus) Nuclear Ribosomal RNA Genes

An under-methylated region in the spacer of ribosomal RNA genes of Lilium henryi

PHYLOGENETICS OF THE LISIANTHIUS SKINNERI (GENTIANACEAE) SPECIES COMPLEX IN PANAMA UTILIZING DNA RESTRICTION FRAGMENT ANALYSIS

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