Plant polytene chromosomes

Carvalheira, Gianna

doi:10.1590/s1415-47572000000400050

Cited by 38 publications

(24 citation statements)

References 58 publications

(70 reference statements)

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“…47, 2004 Endoreplicated and diploid interphase nuclei displayed a similar number of chromocentres, which were much larger in the endoreplicated nuclei, suggesting that the heterochromatic blocks of the endoreplicated chromatids remained very close together. Such a structure, typical of polytenic chromosomes, is reported here in plant holocentric chromosomes for the first time (see Carvalheira 2000). In plant polytenics with monocentric chromosomes, as well as in Drosophila polytenics, the large endochromocentres are associated with the pericentromeric heterochromatin, as in Phaseolus species (Carvalheira and Guerra 1998), but in the present investigation, they seemed to be associated because of the general sticky property of heterochromatin (Pedrosa et al 2001).…”

Section: Discussionsupporting

confidence: 58%

Heterochromatin and rDNA sites distribution in the holocentric chromosomes of Cuscuta approximata Bab. (Convolvulaceae)

Guerra¹,

García²

2004

Genome

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Cuscuta is a widely distributed genus of holoparasitic plants. Holocentric chromosomes have been reported only in species of one of its subgenera (Cuscuta subg. Cuscuta). In this work, a representative of this subgenus, Cuscuta approximata, was investigated looking for its mitotic and meiotic chromosome behaviour and the heterochromatin distribution. The mitotic chromosomes showed neither primary constriction nor Rabl orientation whereas the meiotic ones exhibited the typical quadripartite structure characteristic of holocentrics, supporting the assumption of holocentric chromosomes as a synapomorphy of Cuscuta subg. Cuscuta. Chromosomes and interphase nuclei displayed many heterochromatic blocks that stained deeply with hematoxylin, 4',6-diamidino-2-phenylindole (DAPI), or after C banding. The banded karyotype showed terminal or subterminal bands in all chromosomes and central bands in some of them. The single pair of 45S rDNA sites was observed at the end of the largest chromosome pair, close to a DAPI band and a 5S rDNA site. Two other 5S rDNA site pairs were found, both closely associated with DAPI bands. The noteworthy giant nuclei of glandular cells of petals and ovary wall exhibited large chromocentres typical of polytenic nuclei. The chromosomal location of heterochromatin and rDNA sites and the structure of the endoreplicated nuclei of C. approximata seemed to be similar to those known in monocentric nuclei, suggesting that centromeric organization has little or no effect on chromatin organization.

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Section: Discussionsupporting

confidence: 58%

Heterochromatin and rDNA sites distribution in the holocentric chromosomes of Cuscuta approximata Bab. (Convolvulaceae)

Guerra¹,

García²

2004

Genome

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“…As the method does not require any uniform fluorescence intensity quantification, microscopic parameters could be set for each nucleus for optimal fluorescence recovery. Image acquisition was performed on hybridized slides with confocal laser scanning microscopy as Z-series Figures S2 and S3), such a distribution strongly suggests that each hybridization dot corresponds to a single chromatid, and that sister chromatids remain attached during endoreduplication which leads to the generation of polytenic chromosomes (Zybina and Zybina, 1996;Carvalheira, 2000;Joubè s and Chevalier, 2000;Edgar and Orr-Weaver, 2001;Bourdon et al, 2010).…”

Section: Resultsmentioning

confidence: 99%

In planta quantification of endoreduplication using fluorescent in situ hybridization (FISH)

et al. 2011

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SUMMARYEndopolyploidy, i.e. amplification of the genome in the absence of mitosis, occurs in many plant species and happens along with organ and cell differentiation. Deciphering the functional roles of endopolyploidy is hampered by the fact that polyploid tissues generally comprise cells with various ploidy levels. In some fleshy fruits (amongst them tomato fruit) the ploidy levels present at the end of development range from 2C to 256C in the same tissue. To investigate the temporal and spatial distribution of endopolyploidy it is necessary to address the DNA content of individual nuclei in situ. Conventional methods such as fluorometry or densitometry can be used for some tissues displaying favorable characteristics, e.g. small cells, small nuclei, organization in a monolayer, but high levels of varying polyploidy are usually associated with large sizes of nuclei and cells, in a complex three dimensional (3-D) organization of the tissues. The conventional methods are inadequate for such tissue, becoming semi-quantitative and imprecise. We report here the development of a new method based on fluorescent in situ bacterial artificial chromosome hybridizations that allows the in situ determination of the DNA ploidy level of individual nuclei. This method relies on the counting of hybridization signals and not on intensity measurements and is expected to provide an alternative method for mapping endopolyploidy patterns in mature, 3-D organized plant tissues as illustrated by the analysis of ploidy level and cell size in pericarp from mature green tomato fruit.

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“…The main difference between a normal mitotic cycle and endoreduplication cycle is that during the cell differentiation, no mitosis occurs (Barow 2006;Barow & Jovtchev 2007). Under certain conditions, a cell can switch itself from the mitotic mode to the endoreduplication mode (Carvalheira 2000).…”

Section: Introductionmentioning

confidence: 99%

Endopolyploidy in organs ofTrifolium pratenseL.in different ontogenetic stages

et al. 2014

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Endopolyploidy is a common feature in seed plants. This phenomenon occurs during early development. Flow cytometry of 54 individuals of the species Trifolium pratense variety Manuela, in the vegetative organs during four ontogenetic stages is described. Fresh plant material grown from seeds was used for the analysis. The calculation made on the basis of the mean cycle value revealed that the level of endopolyploidy is different in various organs during the ontogeny. The highest endopolyploidy was recorded in the cotyledons of the first stage (1.0) and the lowest in the third leaf of the fourth ontogenetic stage (0.18). It was noticed that the degree of endopolyploidy decreased during the ontogeny in most of the plants and thus the ontogenetically oldest organs had higher endopolyploidy than the younger ones.

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Plant polytene chromosomes

Cited by 38 publications

References 58 publications

Heterochromatin and rDNA sites distribution in the holocentric chromosomes of Cuscuta approximata Bab. (Convolvulaceae)

Heterochromatin and rDNA sites distribution in the holocentric chromosomes of Cuscuta approximata Bab. (Convolvulaceae)

In planta quantification of endoreduplication using fluorescent in situ hybridization (FISH)

Endopolyploidy in organs ofTrifolium pratenseL.in different ontogenetic stages

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