DNA content in <i>Tradescantia</i>

Martínez, Arturo; Ginzo, H. D.

doi:10.1139/g85-114

Cited by 17 publications

(7 citation statements)

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“…Even here, however, the data set is unrepresentative, being dominated by estimates from just three out of the c. 40 genera (i.e., Tradescantia, 52 species; Gibasis, 17 species; Commelina, 17 species). Nevertheless, given the extensive cytological data available for Commelinaceae (reviewed in [121][122][123]) the upper limit may not be extended considerably as the largest chromosomes so far reported belong to Tradescantia virginiana and its North and Central American allies [124], and the largest genome size estimate available is for tetraploid T. virginiana (2n = 4x = 24) with 1C = 43.4 pg [125]. Indeed the genomes that appear as outliers in Figure 4 Nevertheless, it seems likely that Commelinaceae genomes smaller than 1C = 2.6 pg (for tetraploid Commelina erecta, 2n = 4x = 60) will be uncovered as the smallest chromosomes so far reported are in Stanfieldiella with 2n = 22, Bufforestia (2n = 34) and Cartonema with 2n = 24 [121,122,126].…”

Section: Commelinalesmentioning

confidence: 99%

Genome Size Dynamics and Evolution in Monocots

et al. 2010

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Monocot genomic diversity includes striking variation at many levels. This paper compares various genomic characters (e.g., range of chromosome numbers and ploidy levels, occurrence of endopolyploidy, GC content, chromosome packaging and organization, genome size) between monocots and the remaining angiosperms to discern just how distinctive monocot genomes are. One of the most notable features of monocots is their wide range and diversity of genome sizes, including the species with the largest genome so far reported in plants. This genomic character is analysed in greater detail, within a phylogenetic context. By surveying available genome size and chromosome data it is apparent that different monocot orders follow distinctive modes of genome size and chromosome evolution. Further insights into genome size-evolution and dynamics were obtained using statistical modelling approaches to reconstruct the ancestral genome size at key nodes across the monocot phylogenetic tree. Such approaches reveal that while the ancestral genome size of all monocots was small (1C = 1.9 pg), there have been several major increases and decreases during monocot evolution. In addition, notable increases in the rates of genome size-evolution were found in Asparagales and Poales compared with other monocot lineages.

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Section: Commelinalesmentioning

confidence: 99%

Genome Size Dynamics and Evolution in Monocots

et al. 2010

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“…Thus, in Sowerbaea juncea Sm. from Queensland, Australia 4C = 105 pg (Stewart & Barlow, 1976), while Tradescantia guatemalensis Veil, from Guatemala (Martinez & Ginzo, 1985) has AC = 94-8 pg. Moreover, the large chromosomes in some tropical Crinum spp.…”

Section: Later Developments and Conclusionmentioning

confidence: 99%

Variation in Genomic Form in Plants and Its Ecological Implications

Bennett¹

1987

New Phytologist

356

198

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SUMMARYThe gross form of the nuclear genome varies greatly among plant species in both anatomy and genetic organization. Chromosome number (n) ranges from 2 to over 600, and ploidy from 1 to over 20. The amount of DNA in the unreplicated haplophase genome (the lC value) differs by more than 2500-fold among angiosperms. Although it has been questioned since the 1930s whether such variation is of adaptive significance and whether it is related, perhaps causally, with environmental factors, no direct or causal links have yet been found. However, variation in DNA C-value has far-reaching biological consequences and can be of considerable adaptive and hence ecological significance. Strikingly precise interspecific relationships exist between DNA C-value and many diverse phenotypic characters at the cellular level, and DNA can affect the phenotype in two ways, firstly by expression of its genie content and, secondly, by the biophysical effects of its mass and volume, the latter defined as nucleotypic effects. Nucleotypic variation in DNA C-value sets absolute limits to both the minimum size and mass of the basic unit of plant anatomy (i.e. the cell) and the minumuni time needed to produce a similar cell with newly synthesized organic molecules. Moreover, in complex multicellular vascular plants, such effects at successive cell cycles are additive, so that DNA C-value influences many characters, including growth rate, seed weight, minimum generation time and type of life-cycle. Thus, the nucleotype profoundly affects where, when and how plants grow. Selection for a particular genomic form acting on its spatial or temporal consequences may occur at various levels ranging from the cell to the whole organism and may operate throughout the life-cycle or at just one stage. DNA C-value is often indirectly related to environmental factors which determine time-limited environments via selection acting on the temporal phenotypic consequences of nucleotypic variation. However, in the case of radio-sensitivity, selection for a low DNA C-value may act directly on the nucleotype itself, as the size of the nuclear DNA target directly affects the ability of the plant to survive.Key words: Plant genomic form, DNA C-value, DNA amount, cytoecology, nucleotype. GENOMIC FORM -CONSTANCY AND VARIATIONMany great discoveries in biology this century have concerned the genome and its form -that the genetic material is DNA, that this has a double helical structure, that this form is important in semi-conservative replication and cell heredity, and that the genetic code is written as triplets of nucleotides. In these important respects, genomic form is the same in all eukaryotes. These discoveries emphasized aspects of constancy in genomic form, except for the nucleotide base sequences of genie DNA whose variation determines the phenotype. However, much cytological work also showed that the genome can vary greatly in both anatomy and genetic organization among taxa.This review is concerned with variation in aspects of gross genomic form in nuclei...

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“…Even when a stronger compaction of DNA in polyploid nuclei produces an underestimate of the measurements (Verma and Rees, 1974;Kenton, 1984b) it has been observed in several cases that polyploids have smaller chromosomes and lower DNA content than the expected (Darlington, 1965;Grant, 1976Grant, , 1987Bennett, 1987;MartInez and Ginzo, 1985;Poggio and Hunziker, 1986; Poggio and Naranjo, in press). In Larrea due to the very small size of its chromosomes it is not known whether the diminution affects all chromosomes or only part of the complement.…”

Section: Resultsmentioning

confidence: 99%

Nuclear DNA variation in diploid and polyploid taxa of Larrea (Zygophyllaceae)

1989

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A study of nuclear DNA content was made in telophase nuclei (2C) of the root apex of germinating seed in nine populations of the following species and cytotypes of Larrea: L. nitida (2x), L. divaricata (2x), L. cuneifolia (4x) and L. tridentata (2x, 4x, 6x). There were no significant differences in DNA content per basic monoploid genome among the diploid taxa nor between the latter and the tetraploid, among tetraploids or between tetraploids and the hexaploid. On the other hand, the difference between means was significant when all diploids were compared with the hexaploid cytotype. These results would indicate: (I) Speciation at the diploid level in Larrea has not produced great differences in DNA content per basic genome. This is in contrast with the related genus Bulnesia.

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DNA content in Tradescantia

Cited by 17 publications

References 0 publications

Genome Size Dynamics and Evolution in Monocots

Genome Size Dynamics and Evolution in Monocots

Variation in Genomic Form in Plants and Its Ecological Implications

Nuclear DNA variation in diploid and polyploid taxa of Larrea (Zygophyllaceae)

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