Genetic control of 1R nucleolus organizer region expression in the presence of wheat genomes

Vieira, R.; Queiroz, Álvaro Antônio Alencar de; Morais, L.; Barão, Augusta; Mello-Sampayo, T.; Viegas, Wanda

doi:10.1139/g90-107

Cited by 38 publications

(27 citation statements)

References 12 publications

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“…An examination of N. rustica root-tip cells without pretreatment shows that the decondensed rDNA is more dispersed, but the profile of locus decondensation remained similar with silent sites unassociated with nucleoli apparent at interphase (Figure 2 i-l). Thus, the rDNA loci of N. rustica show variable activity both between and within loci as reported for other plant species (Vieira et al, 1990) and that the least active sites appear to occur on P-genome chromosomes.…”

Section: Resultssupporting

confidence: 68%

“…Similarly, in N. tabacum the minority N. sylvestris-type units are heavily methylated (Lim et al, 2000b). Heavily methylated units are not usually active at interphase; indeed inactive rDNA loci can be experimentally activated by the addition of demethylating agents (Vieira et al, 1990;Chen and Pikaard, 1997). If Lim et al (2000b) are correct, then it can be predicted that there is lower activity of the rDNA loci on the P-genome chromosomes of N. rustica and this is a factor contributing to the maintenance of some N. paniculata-like units in the allotetraploid.…”

Section: Discussionmentioning

confidence: 99%

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Ribosomal DNA evolution and gene conversion in Nicotiana rustica

et al. 2003

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Genomic in situ hybridisation was used to confirm that Nicotiana rustica (2n ¼ 4x ¼ 48) is an allotetraploid between N. paniculata (2n ¼ 2x ¼ 24, maternal P-genome donor) and N. undulata (2n ¼ 2x ¼ 24, paternal U-genome donor), their progenitors or species closely related to them. Fluorescent in situ hybridisation showed that N. paniculata has one 5S and two 18-5.8-26S rDNA loci whereas N. undulata has an additional 18-5.8-26S rDNA locus. N. rustica has the sum of the loci found in these putative parents. The sizes of the 18-5.8-26S rDNA loci indicate that the number of rDNA units on the U-genome chromosomes has amplified; perhaps this is associated with a concomitant reduction in the number of units on P-genome chromosomes. Restriction fragment length polymorphism analysis of the intergenic spacer (IGS) of the 18-5.8-26S rDNA units in N. rustica and the two progenitor diploids revealed that about 80% of IGS sequences in N. rustica are of an N. undulata type and 20% of N. paniculata type. These data indicate that interlocus sequence homogenisation has caused the replacement of many N. paniculata-type IGSs in N. rustica with an N. undulata-type of sequence. It is probable that subsequent to this replacement there has been sequence divergence at the 5 0 end of the IGS. As in tobacco, an allotetraploid between N. sylvestris and N. tomentosiformis, the direction of the IGS interlocus conversion is towards the paternal genome donor.

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Section: Resultssupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Ribosomal DNA evolution and gene conversion in Nicotiana rustica

et al. 2003

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“…The silver staining technique employed was that described by Vieira et al (1990). After cold treatment, roots were fixed in 50% ethanol, glacial acetic acid and 37% formaldehyde (18:1:1, v/v/v) for a minimum of 4 h at room temperature and a maximum of three days at 0°C to 2°C.…”

Section: Silver Stainingmentioning

confidence: 99%

“…The activity of 45S rDNA genes is usually associated with NORs and secondary constrictions, and has been studied at cytological level by recording the number and volume of nucleoli in interphase cells and NORs in metaphase chromosomes by silver staining (Martini and Flavell, 1985;Vieira et al, 1990;Lima-Brito et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Chromosome characterization in Thinopyrum ponticum (Triticeae, Poaceae) using in situ hybridization with different DNA sequences

et al. 2003

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Thinopyrum ponticum (2n = 10x = 70, JJJJ s J s ) belongs to the Triticeae tribe, and is currently used as a source of pathogen resistance genes in wheat breeding. In order to characterize its chromosomes, the number and position of 45S and 5S rDNA sites, as well as the distribution of the repetitive DNA sequences pAs1 and pSc119.2, were identified by fluorescent in situ hybridization. The number of nucleoli and NORs was also recorded after silver nitrate staining. Seventeen 45S and twenty 5S rDNA sites were observed on the short arms of 17 chromosomes, the 45S rDNA was always located terminally. On three other chromosomes, only the 5S rDNA site was observed. Silver staining revealed a high number of Ag-NORs (14 to 17) on metaphase chromosomes, whereas on interphase nuclei there was a large variation in number of nucleoli (one to 15), most of them (82.8%) ranging between four and nine. The pAs1 probe hybridized to the terminal region of both arms of all 70 chromosomes. In addition, a disperse labeling was observed throughout the chromosomes, except in centromeric and most pericentromeric regions. When the pSc119.2 sequence was used as a probe, terminal labeling was observed on the short arms of 17 chromosomes and on the long arms of five others. The relative position of 45S and 5S rDNA sites, together with the hybridization pattern of pAs1 and pSc119.2 probes, should allow whole chromosomes or chromosome segments of Th. ponticum to be identified in inbred lines of wheat x Th. ponticum.

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“…Estimates of genome size, which are currently addressed mostly by comparing the relative fluorescence of propidium iodide stained nuclei measured in a flow cytometer to that of known patterns, are compiled in the Kew C-value database (Doležel and Greilhuber 2010;Garcia et al 2014a). Other valuable information such as: karyotype formula, dependent on the relative position of centromere along the chromosome and chromosome length (Guerra 1986), silver staining of nucleolar organizer regions (AgNOR) (Vieira et al 1990), and heterochromatin staining after treatment with acids, bases or denaturation (Schwarzacher et al 1980;Guerra 2000; Barros e Silva and Guerra 2010) are not included in databases. In contrast, fluorescence in situ hybridization (FISH), in which a DNA probe produced by molecular biology methods anneals with chromosome preparations and is detected by fluorescence has gained more attention (Roa and Guerra 2012;Garcia et al 2014b;Roa and Guerra 2015).…”

Section: Introductionmentioning

confidence: 99%

The Cerrado (Brazil) plant cytogenetics database

Roa¹,

Telles²

2017

CCG

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Cerrado is a biodiversity hotspot that has lost ca. 50% of its original vegetation cover and hosts ca. 11,000 species belonging to 1,423 genera of phanerogams. For a fraction of those species some cytogenetic characteristics like chromosome numbers and C-value were available in databases, while other valuable information such as karyotype formula and banding patterns are missing. In order to integrate and share all cytogenetic information published for Cerrado species, including frequency of cytogenetic attributes and scientometrics aspects, Cerrado plant species were searched in bibliographic sources, including the 50 richest genera (with more than 45 taxa) and 273 genera with only one species in Cerrado. Determination of frequencies and the database website (http://cyto.shinyapps.io/cerrado) were developed in R. Studies were pooled by employed technique and decade, showing a rise in non-conventional cytogenetics since 2000. However, C-value estimation, heterochromatin staining and molecular cytogenetics are still not common for any family. For the richest and best sampled families, the following modal 2n counts were observed: Oxalidaceae 2n = 12, Lythraceae 2n = 30, Sapindaceae 2n = 24, Solanaceae 2n = 24, Cyperaceae 2n = 10, Poaceae 2n = 20, Asteraceae 2n = 18 and Fabaceae 2n = 26. Chromosome number information is available for only 16.1% of species, while there are genome size data for only 1.25%, being lower than the global percentages. In general, genome sizes were small, ranging from 2C = ca. 1.5 to ca. 3.5 pg. Intraspecific 2n number variation and higher 2n counts were mainly related to polyploidy, which relates to the prevalence of even haploid numbers above the mode of 2n in most major plant clades. Several orphan genera with almost no cytogenetic studies for Cerrado were identified. This effort represents a complete diagnosis for cytogenetic attributes of plants of Cerrado.

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Genetic control of 1R nucleolus organizer region expression in the presence of wheat genomes

Cited by 38 publications

References 12 publications

Ribosomal DNA evolution and gene conversion in Nicotiana rustica

Ribosomal DNA evolution and gene conversion in Nicotiana rustica

Chromosome characterization in Thinopyrum ponticum (Triticeae, Poaceae) using in situ hybridization with different DNA sequences

The Cerrado (Brazil) plant cytogenetics database

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