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Journal ArticleDOI

Chromosome banding in evolutionary plant cytogenetics

01 Feb 1983-Vol. 92, Iss: 1, pp 51-79
TL;DR: The introduction of chromosome banding techniques for linear differentiation of chromosomes have allowed the identification of the heterochromatic segments on the chromosomes, which have been utilized for inter- and intra-species comparisons and the probable phylogenetic relationships in various plant taxa from Gymnosperms, Angiosperms have been suggested.
Abstract: The introduction of chromosome banding techniques for linear differentiation of chromosomes have allowed the identification of the heterochromatic segments on the chromosomes. These heterochromatic segments are primarily composed of repetitive DNA, which are discernible in the form of dark staining regions by Giemsa C band staining or exhibit enhanced or reduced fluorescent bands by Q banding techniques depending upon the particular type of DNA repetition. The analyses of banding patterns have allowed in plants, the identification of chromosomes or parts of chromosomes, which have been utilized for inter- and intra-species comparisons. Based on the information of banding patterns, amount and distribution of heterochromatic segments, coupled with karyotypic features and morphological similarities; the probable phylogenetic relationships in various plant taxa from Gymnosperms, Angiosperms (both dicots and monocots) have been suggested. The information on heterochromatin recognition have also been utilized in suggesting probable ancestry of polyploids and the trend of evolution in varietal differentiation and speciation. Analysing the data, a probable phylogenetic significance and the direction of change in heterochromatin evolution in plants is suggested.
Topics: G banding (66%), Karyotype (55%), Cytogenetics (54%), Heterochromatin (53%), Chromosome (51%)
Citations
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01 Jan 1979-
Abstract: Dispersed repetitive DNA sequences from yeast (Saccharomyces cerevisiae) nuclear DNA have been isolated as molecular hybrids in lambdagt. Related S. cerevisiae strains show marked alterations in the size of the restriction fragments containing these repetitive DNAs. "Ty1" is one such family of repeated sequences in yeast and consists of a 5.6 kilobase (kb) sequence including a noninverted 0.25 kb sequence of another repetitious family, "delta", on each end. There are about 35 copies of Ty1 and at least 100 copies of delta (not always associated with Ty1) in the haploid genome. A few Ty1 elements are tandem and/or circular, but most are disperse and show (along with delta) some sequence divergence between repeat units. Sequence alterations involving Ty1 elements have been found during the continual propagation of a single yeast clone over the course of a month. One region with a large number of delta sequences (SUP4) also shows a high frequency of sequence alterations when different strains are compared. One of the differences between two such strains involves the presence or absence of a Ty1 element. The novel joint is at one inverted pair of delta sequences.

383 citations


Journal ArticleDOI
01 Aug 1994-Genome
TL;DR: There seemed to be a trend for reduction in C-heterochromatin content in the course of evolution in Cicer, and C-banding patterns allowed for chromosome identification and matching pairs of homologues in all species analyzed.
Abstract: Somatic karyotypes of the nine annual species of Cicer (2n = 16) were analyzed using C-banding. Highly significant differences in haploid genome length and C-band positive heterochromatin content were observed. The haploid genome length ranged from 20.0 μm in the wild species C. judaicum to 28.7 μm in the cultivated species C. arietinum, and significant differences for this character were observed between accessions within several species. Based on their heterochromatin content, the species were divided into two groups: low heterochromatin content (average of 41.7%), which included C. arietinum, C. chorassanicum, C. echinospermum, C. judaicum, C. pinnatifidum, C. reticulatum, and C. yamashitae, and high heterochromatin content (average of 59.5%), which included C. bijugum and C. cuneatum. Within-group variation for heterochromatin content was insignificant, while differences between groups were highly significant. There seemed to be a trend for reduction in C-heterochromatin content in the course of evolution in Cicer. In all species studied, C-bands were located proximally around the centromere with occasional bands in intercalary and distal positions. C-banding patterns allowed for chromosome identification and matching pairs of homologues in all species analyzed.

39 citations


Book ChapterDOI
TL;DR: The significance of the 4C value (where C is the amount of DNA in the unreplicated haploid genome) in angiosperm plants is discussed and some rules governing the distribution of DNA amount among different plant taxa are postulated.
Abstract: The significance of the 4C value (where C is the amount of DNA in the unreplicated haploid genome) in angiosperm plants is discussed. The DNA amount is a stable feature used in biosystematics. Although this parameter varies even in closely related taxa, there is no correlation between the DNA amount and the structural and functional organization of plants. The role of DNA amount, including "excess" DNA, in plant evolution is considered. Some rules governing the distribution of DNA amount among different plant taxa are postulated, together with the possibility of using the data in systematics, phylogeny, and solutions of problems of genetic apparatus organization and evolution. The decrease in DNA value per genome during plant evolution and the high level of species formation in taxa with large DNA values have been shown. Plant taxa with a small DNA value per genome have a high percentage and higher degree of polyploidy. The nature of the differential staining of euchromatin and heterochromatin bands of prophase and metaphase chromosomes is also discussed. Data that could explain the mechanism of heterochromatin visualization under cold pretreatment of cells are reviewed. Phenomena involved in the arrangement of chromocenters in interphase nuclei and chromosomes in metaphase during consecutive cell generations are discussed.

27 citations


Journal ArticleDOI
25 Mar 1989-Cytologia
TL;DR: Interphase nuclear organization was studied in six species of Cicer and all the species showed chromocentric nuclear organization in both meristematic and differentiated cells instead of reticulate organization, which can be considered as primitive of the six Cicer species.
Abstract: Interphase nuclear organization was studied in six species of Cicer and all the species showed chromocentric nuclear organization in both meristematic and differentiated cells instead of reticulate organization. The number of chromocentres and treatment duration with acid or alkali were found to be species specific character. Percentage heterochromatin values determined by two different techniques were somewhat high in meristematic cells than those in differentiated cells. On the basis of heterochromatin values both in meristematic and differentiated cells C. reticulaturn can be considered as primitive of the six Cicer species. Nuclear organization was found to be governed by small size of chromosomes and low DNA content, but the relationship between heterochromatin values and DNA content was not clear.

7 citations


Journal ArticleDOI
TL;DR: Nuclear and chromosome characteristics of seven varieties of Colocasia esculenta were studied and revealed that somatic chromosome number was 28 in cytotype-1, 2, 5, 6 and 7; 42 in cytotyp-3 and 21 in cytotypes-4.
Abstract: Nuclear and chromosome characteristics of seven varieties of Colocasia esculenta were studied. Interphase chromosome value was found to range from 2119.85 (cytotype-3) to 5346.12 (cytotype-7). Heterochromatin values varied from 23.17 (cytotype-2) to 44.52% (cytotypt-6) in meristematic cells. Karyotype studies revealed that somatic chromosome number was 28 in cytotype-1, 2, 5, 6 and 7; 42 in cytotype-3 and 21 in cytotype-4. The longest chromosome (5.54 μm) was observed in cytotyopt-2 and shortest (1.3 μm) in cytotype-3 and 6. Key words: Karyotype, Nuclear phenotype, Colocasia esculenta. DOI:10.3329/jbs.v16i0.3735 J. bio-sci. 16: 15-18, 2008

6 citations


References
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Book
01 Jan 1971-

2,627 citations


Journal ArticleDOI
17 Apr 1980-Nature
TL;DR: The DNA of higher organisms usually falls into two classes, one specific and the other comparatively nonspecific, and it seems plausible that most of the latter originated by the spreading of sequences which had little or no effect on the phenotype.
Abstract: The DNA of higher organisms usually falls into two classes, one specific and the other comparatively nonspecific. It seems plausible that most of the latter originates by the spreading of sequences which had little or no effect on the phenotype. We examine this idea from the point of view of the natural selection of preferred replicators within the genome.

1,852 citations


Journal ArticleDOI
17 Apr 1980-Nature
TL;DR: Natural selection operating within genomes will inevitably result in the appearance of DNAs with no phenotypic expression whose only ‘function’ is survival within genomes.
Abstract: Natural selection operating within genomes will inevitably result in the appearance of DNAs with no phenotypic expression whose only ‘function’ is survival within genomes. Prokaryotic transposable elements and eukaryotic middle-repetitive sequences can be seen as such DNAs, and thus no phenotypic or evolutionary function need be assigned to them.

1,650 citations


"Chromosome banding in evolutionary ..." refers background in this paper

  • ...Dover and Doolittle (1980) emphasize that, in establishing these processes, evolution has inadvertently endowed the genome with built-in mechanisms for irregular and recurrent random sequence rearrangements and created an environment in which elements capable (to varying extents) of promoting their own amplification and dispersion will inevitably arise (Dover 1977; Doolittle and Sapienza 1980; Orgel and Crick 1980)....

    [...]


Journal ArticleDOI
13 Feb 1976-Science
TL;DR: Qualitatively, then, unequal crossover provides a reasonable and uncontrived explanation for the prevalence of highly repeated sequences in DNA and for the patterns of periodicity they evince.
Abstract: It is often supposed that highly repetitious DNA's arise only as a result of unusual mechanisms or in response to selective pressure. My arguments and simulations suggest, by contrast, that a pattern of tandem repeats is the natural state of DNA whose sequence is not maintained by selection. The simulations show that periodicities can develop readily from nonreptitious DNA as a result of the random accumulation of random mutations and random homology-dependent unequal crossovers. The lengths of these periodicities, and the patterns of subrepeats within them, would fluctuate in evolution, with the probability of a given pattern being dependent on the unknown exact nature of the crossover mechanism. Qualitatively, then, unequal crossover provides a reasonable and uncontrived explanation for the prevalence of highly repeated sequences in DNA and for the patterns of periodicity they evince.

1,109 citations


Journal ArticleDOI
01 Apr 1979-Cell
Abstract: Dispersed repetitive DNA sequences from yeast (Saccharomyces cerevisiae) nuclear DNA have been isolated as molecular hybrids in lambdagt. Related S. cerevisiae strains show marked alterations in the size of the restriction fragments containing these repetitive DNAs. "Ty1" is one such family of repeated sequences in yeast and consists of a 5.6 kilobase (kb) sequence including a noninverted 0.25 kb sequence of another repetitious family, "delta", on each end. There are about 35 copies of Ty1 and at least 100 copies of delta (not always associated with Ty1) in the haploid genome. A few Ty1 elements are tandem and/or circular, but most are disperse and show (along with delta) some sequence divergence between repeat units. Sequence alterations involving Ty1 elements have been found during the continual propagation of a single yeast clone over the course of a month. One region with a large number of delta sequences (SUP4) also shows a high frequency of sequence alterations when different strains are compared. One of the differences between two such strains involves the presence or absence of a Ty1 element. The novel joint is at one inverted pair of delta sequences.

443 citations


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