Some aspects of plant karyology and karyosystematics.
01 Jan 2000-International Review of Cytology-a Survey of Cell Biology (Int Rev Cytol)-Vol. 196, pp 131-175
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.
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01 Jan 2013
TL;DR: Surprisingly, many accepted trends between polyploidy and geography, mating system, and comparative rates of species diversification have become less strong or conflicting with the development of new procedures, in particular with phylogenetic approaches.
Abstract: Polyploidy, the multiplication of chromosome sets above the diploid state, is arguably as prevalent in plants as any other eukaryotic group. Over the past century, polyploidy has been linked with particular taxonomic groups (flowering plants, ferns), northern latitudes and extreme environments, and life histories such as perenniality, asexuality and self-fertilization. Here we review the current state of evidence for these patterns and their interpretations. Our understanding of the incidence of polyploidy in plants is still in flux due to a progression of advances in cytogenetics, flow cytometry, phylogenetics and genomics. We find polyploidy to be highly heterogeneous among plant groups and estimates of intraspecific variation and hybrid forms are increasing with high throughput analyses. Surprisingly, many accepted trends between polyploidy and geography, mating system, and comparative rates of species diversification have become less strong or conflicting with the development of new procedures, in particular with phylogenetic approaches. Our review suggests that while some patterns remain strong, many are not universal, suggesting there may be no unified explanation for the success of polyploids in plants.
172 citations
TL;DR: Overall, the large-scale analyses of karyotype features within a well-supported phylogenetic framework enabled the most likely patterns of chromosome evolution in Liliaceae to be reconstructed, highlighting diverse modes of kARYotype evolution, even within this comparatively small monocot family.
172 citations
Cites background from "Some aspects of plant karyology and..."
...Grif VG. 2000....
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...Total form % TF% Huziwara (1962) Index of chromosome size resemblance Rec Greilhuber and Speta (1976) Index of karyotype symmetry Syi Greilhuber and Speta (1976) Karyotype dispersion index DI Lavania and Srivastava (1992) Degree of karyotype asymmetry A Watanabe et al....
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01 Jan 2013
TL;DR: It is clear that polyploidy plays only a relatively small role in the origin of the huge genome size differences reported, and the accumulation of retroposon-like and other repetitive elements in the genomes which are largely responsible for the huge diversity of genome sizes in plants.
Abstract: Land plant species (Embryophyta) vary more than 2,300-fold in the size of the holoploid genome (C-value) (see Leitch and Leitch 2012a, this volume) with the extremes at both ends of the scale contributed by angiosperms. At the lower end we find some species of the carnivorous Lentibulariaceae with ultrasmall genomes, e.g. Genlisea aurea with 0.065 pg or 63.5 Mbp (1C) (Greilhuber et al. 2006). This is only about 0.40-fold the size of the genome of Arabidopsis thaliana with 0.16 pg or 156.5 Mbp (1C) (Bennett et al. 2003), a species long considered to be the plant with the smallest reliably determined genome size. At the upper end of the scale stands the monocot octoploid Paris japonica (Melanthiaceae) with 2n = 8x = 40 and 152.23 pg or 148.88 Gbp (1C) (Pellicer et al. 2010). Nevertheless, other monocot species such as Fritillaria davisii (69.45 pg, 1C; 2n = 2x = 24, a possible palaeotetraploid), Trillium apetalon (95.0 pg, 1C; 2n = 4x = 20), and the dicot tree parasite Viscum album (102.9 pg, 1C; 2n = 20, palaeotetraploid?) also rank high on the scale regarding monoploid genome size (i.e. Cx-value = 2C-value divided by ploidy level) (Zonneveld 2010). From these examples it is clear that polyploidy plays only a relatively small role in the origin of the huge genome size differences reported. Instead, it is the accumulation of retroposon-like and other repetitive elements in the genomes which are largely responsible for the huge diversity of genome sizes in plants (Bennetzen et al. 2005; Grover and Wendel 2010; see also Kejnovsky et al. 2012 in Volume 1). (N.B. Recent studies using flow cytometry to estimate genome size in species with enormous genomes have highlighted how the more traditional approach of estimation using Feulgen densitometry may considerably underestimate genome size at this upper end of the scale (Zonneveld 2010).)
91 citations
TL;DR: The understanding of why B chromosomes are present in some species and absent in others is still in its infancy, and several potential avenues for future research are suggested.
Abstract: In this review we look at the broad picture of how B chromosomes are distributed across a wide range of species. We review recent studies of the factors associated with the presence of Bs across speci
69 citations
Cites background from "Some aspects of plant karyology and..."
...Another possible, though less likely, explanation is suggested by the fact that average DNA amount per diploid genome is negatively correlated with the prevalence of polyploidy (Grif, 2000)....
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TL;DR: A high level of H3 phosphorylation along the whole mitotic chromosome after cantharidin treatment is revealed, which resembles the distribution seen exclusively in first meiotic division.
Abstract: The function of the phosphorylation of histone H3 at Ser 10 in plant cell division is uncertain. The timing correlates with chromosome condensation, and studies in plant meiosis suggest that it is involved in sister chromatid cohesion. In mitosis, plant chromosomes are highly phosphorylated in the pericentromeric region only. In order to modulate H3 phosphorylation, root meristems of different plant species were treated with the protein phosphatase inhibitor cantharidin or with ice-water. Immunostaining using an antibody specific to phosphorylated H3 at Ser 10 revealed a high level of H3 phosphorylation along the whole mitotic chromosome after cantharidin treatment, which resembles the distribution seen exclusively in first meiotic division. In chromosomes that were isolated from meristems treated with ice-water, the heterochromatic regions and nucleolar organizer regions, in addition to the pericentromeric region, were highly phosphorylated at H3. Cantharidin and ice-water also affected spindle assembly and chromosome length, but these effects did not seem to be directly linked to changes in H3 phosphorylation.
45 citations
Cites background from "Some aspects of plant karyology and..."
...It is thought that cold-sensitive regions are a result of local heterochromatin decondensation (Grif 2000)....
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...As in V. faba, additional cold-induced H3-phosphorylated chromatin was detected in AT-rich heterochromatic regions (Grif 2000) of T. camschatcense (Figure 4 g, i, j)....
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...To elucidate whether ice water treatment induces high H3 phosphorylation in distinct chromosome regions only, Trillium camschatcense (Grif 2000), a species with individually distinguishable chromosomes andde¢nedGiemsa/ DAPI-positive heterochromatic regions, was included in this study....
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References
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TL;DR: This paper lists absolute nuclear DNA amounts for 753 angiosperm species, primarily for reference purposes, and so the species are listed in alphabetical order, as this was felt to be more helpful to cyto- and biochemists whom, it is anticipated, will be among its major users.
Abstract: The number of angiosperm species for which nuclear DNA amount estimates have been made has nearly trebled since the last collected lists of such values were published, and therefore, publication of a more comprehensive list is overdue. This paper lists absolute nuclear DNA amounts for 753 angiosperm species. The data were assembled primarily for reference purposes, and so the species are listed in alphabetical order, as this was felt to be more helpful to cyto- and biochemists whom, it is anticipated, will be among its major users. The paper also reviews aspects of the history, nomenclature, methods, accuracy and problems of nuclear DNA estimation in angiosperms. No attempt is made to reconsider those aspects of nuclear DNA estimation which have been fully revised previously, although the bibliography of such aspects is given. Instead, the paper is intended as a source of basic information regarding the terminology, practice and limitations of nuclear DNA estimation, especially by Feulgen microdensitometry, as currently practiced.
1,552 citations
TL;DR: This paper lists absolute nuclear DNA amounts for 753 angiosperm species, and the dats were assembled primarily for reference purposes, and so the species are listed in alphabetical order, as this was felt to be more helpful to cyto- and biochemists whom, it is anticipated, will be among its major users.
1,102 citations
TL;DR: Estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size as a proxy for cellular DNA content suggested that seven to nine is the primitive haploid chromosome number of angios perms and that most angiosPerms (approximately 70 percent) have polyploidy in their history.
Abstract: Three published estimates of the frequency of polyploidy in angiosperms (30 to 35 percent, 47 percent, and 70 to 80 percent) were tested by estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size as a proxy for cellular DNA content. The inferred chromosome numbers of these extinct species suggest that seven to nine is the primitive haploid chromosome number of angiosperms and that most angiosperms (approximately 70 percent) have polyploidy in their history.
1,076 citations
Book•
01 Jan 1997
TL;DR: The culmination of more than fifty years of research by the foremost living expert on plant classification, Diversity and Classification of Flowering Plants is an important contribution to the field of plant taxonomy.
Abstract: The culmination of more than fifty years of research by the foremost living expert on plant classification, Diversity and Classification of Flowering Plants is an important contribution to the field of plant taxonomy. In the last decade, the system of classifying plants has been thoroughly revised. Instead of describing every individual family, Takhtajan includes descriptions in keys to families, which he calls "descriptive keys." The advantage of descriptive keys is that they give both the characteristic features of the families and their differences. The delimitation of families and orders drastically differs from the one accepted by the Englerian school and from the one accepted in Arthur Cronquist's system. Takhtajan favors the smaller, more natural families and orders, which are more coherent and better-defined, where characters are easily grasped, and which are more suitable for information retrieval and phylogenetic studies, including cladistic analysis (because it reduces polymorphic codings).
954 citations
TL;DR: It is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species, and that satellite DNA is significant in its nucleotypic effects on developmental processes.
Abstract: Many components of cell and nuclear size and mass are correlated with nuclear DNA content in plants, as also are the durations and rates of such developmental processes as mitosis and meiosis. It is suggested that the multiple effects of the mass of nuclear DNA which affect all cells and apply throughout the life of the plant can together determine the minimum generation time for each species. The durations of mitosis and of meiosis are both positively correlated with nuclear DNA content and, therefore, species with a short minimum generation time might be expected to have a shorter mean cell cycle time and mean meiotic duration, and a lower mean nuclear DNA content, than species with a long mean minimum generation time. In tests of this hypothesis, using data collated from the literature, it is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species. Furthermore, the mean nuclear DNA content of annual species is significantly lower than for perennial species both in dicotyledons and monocotyledons. Ephemeral species have a significantly lower mean nuclear DNA content than annual species. Among perennial monocotyledons the mean nuclear DNA content of species which can complete a life cycle within one year (facultative perennials) is significantly lower than the mean nuclear DNA content of those which cannot (obligate perennials). However, the mean nuclear DNA content of facultative perennials does not differ significantly from the mean for annual species. It is suggested that the effects of nuclear DNA content on the duration of developmental processes are most obvious during its determinant stages, and that the largest effects of nuclear DNA mass are expressed at times when development is slowest, for instance, during meiosis or at low temperature. It has been suggested that DNA influences development in two ways, directly through its informational content, and indirectly by the physical-mechanical effects of its mass. The term 'nucleotype' is used to describe those conditions of the nucleus which effect the phenotype independently of the informational content of the DNA. It is suggested that cell cycle time, meiotic duration, and minimum generation time are determined by the nucleotype. In addition, it may be that satellite DNA is significant in its nucleotypic effects on developmental processes.
710 citations