Breeding system and genome size of the rhabdocoel turbellarian Mesostoma ehrenbergii

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 719-724 ◽  
Author(s):  
Paul D. N. Hebert ◽  
Margaret J. Beaton
Keyword(s):  
Chromosome Number ◽  
Genome Size ◽  
Breeding System ◽  
New World ◽  
Natural Populations ◽  
Resting Eggs ◽  
Chromosome Counts ◽  
Natural Conditions ◽  
Self Fertilization ◽  
European Populations

Rhabdocoel turbellarians, such as Mesostoma ehrenbergii, are hermaphrodites which produce both subitaneous and resting eggs. Both genotypic frequencies in natural populations as well as parent–offspring genotypes at a polymorphic allozyme locus confirm that, under natural conditions, M. ehrenbergii produces subitaneous eggs via self-fertilization and resting eggs probably by outcrossing. Chromosome counts show, contrary to an earlier report, that North American populations of the species possess the same chromosome number as European populations. However, other karyotypic differences do exist between Old World and New World populations. DNA quantification studies revealed that M. ehrenbergii possesses one of the largest haploid genome sizes (14.8 pg) yet reported for an invertebrate. Among organisms showing similar genome size, this species appears to be unique for its rapid developmental rate.Key words: Turbellaria, allozyme, breeding system, genome size, cytogenetics, selfing.

B chromosomes and genome size in flowering plants

Genome ◽  
2004 ◽  
Vol 47 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Robert Trivers ◽  
Austin Burt ◽  
Brian G Palestis
Keyword(s):  
Logistic Regression ◽  
Regression Analysis ◽  
Chromosome Number ◽  
Genome Size ◽  
Breeding System ◽  
Flowering Plants ◽  
B Chromosomes ◽  
Global Level ◽  
Selfish Genetic Elements ◽  
Large Genomes

B chromosomes are extra chromosomes found in some, but not all, individuals within a species, often maintained by giving themselves an advantage in transmission, i.e. they drive. Here we show that the presence of B chromosomes correlates to and varies strongly and positively with total genome size (excluding the Bs and corrected for ploidy) both at a global level and via a comparison of independent taxonomic contrasts. B chromosomes are largely absent from species with small genomes; however, species with large genomes are studied more frequently than species with small genomes and Bs are more likely to be reported in well-studied species. We controlled for intensity of study using logistic regression. This regression analysis also included effects of degree of outbreeding, which is positively associated with Bs and genome size, and chromosome number, which is negatively associated with Bs and genome size, as well as variable ploidy (more than one ploidy level in a species). Genome size, breeding system and chromosome number all contribute independently to the distribution of B chromosomes, while variable ploidy does not have a significant effect. The genome size correlates are consistent with reduced selection against extra DNA in species with large genomes and with increased generation of B sequences from large A genomes.Key words: B chromosomes, genome size, selfish genetic elements, breeding system, ploidy.

scholarly journals Cytological Study of Cypripedium japonicum Thunb. (Orchidaceae Juss.): An Endangered Species from Korea

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1978
Author(s):  
Bokyung Choi ◽  
Geun-Hye Gang ◽  
Hyeonjin Kim ◽  
Hyejoo Byun ◽  
Minyeong Kwak ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Endangered Species ◽  
Genome Size ◽  
Natural Populations ◽  
Orchid Species ◽  
Chinese Populations ◽  
Cytological Data ◽  
Slipper Orchid ◽  
Base Chromosome Number ◽  
First Time

Changes in chromosome number and karyotype evolution are important to plant diversification, as they are both major drivers of speciation processes. Herein, chromosome number, karyotype, and genome size of the Korean lady’s slipper orchid Cypripedium japonicum Thunb., an endangered species, were investigated in natural populations. Furthermore, all cytological data from this species are reported herein for the first time. The chromosome number of all investigated C. japonicum plants was diploid (2n = 2x = 22), with x = 11 as base chromosome number, whereby the species can now be clearly distinguished from the Japanese lady’s slipper orchid. The karyotypes of all studied individuals were of similar length, symmetrical, and rather unimodal. Flow cytometry of the C. japonicum revealed that the genome size ranged from 28.38 to 30.14 pg/1C. Data on chromosome number and karyotypes were largely consistent with previous results indicating that Korean (x = 11) populations of C. japonicum are more closely related to Chinese populations (x = 11) compared to Japanese (x = 10) populations. These comprehensive cytological results will benefit the efforts to discriminate the geographically isolated and endangered Eastern Asian (China, Japan, and Korea) lady’s slipper orchid species.

scholarly journals Genome Size Estimates and Chromosome Numbers of Callicarpa L. (Lamiaceae)

HortScience ◽  
2011 ◽  
Vol 46 (4) ◽  
pp. 567-570 ◽  
Author(s):  
Ryan N. Contreras ◽  
John M. Ruter
Keyword(s):  
Flow Cytometry ◽  
Chromosome Number ◽  
Genome Size ◽  
Chromosome Numbers ◽  
Chromosome Counts ◽  
Ploidy Levels ◽  
Flow Cytometry Data ◽  
Carbol Fuchsin ◽  
Cross Compatibility ◽  
Size Estimates

Genome size estimates and chromosome number information can be useful for studying the evolution or taxonomy of a group and also can be useful for plant breeders in predicting cross-compatibility. Callicarpa L. is a group of ≈140 species with nearly worldwide distribution. There are no estimates of genome size in the literature and the information on chromosome numbers is limited. Genome size estimates based on flow cytometry are reported here for 16 accessions of Callicarpa comprising 14 species in addition to chromosome counts on six species. Chromosome counts were conducted by staining meristematic cells of roots tips using modified carbol fuchsin. Holoploid genome size estimates ranged from 1.34 pg to 3.48 pg with a mean of 1.74 pg. Two tetraploids (2n = 4x = 68; C. salicifolia P'ei & W. Z. Fang and C. macrophylla Vahl GEN09-0081) were identified based on holoploid genome size and confirmed by chromosome counts. There was little variation among species for monoploid genome size. 1Cx-values ranged from 0.67 pg to 0.88 pg with a mean of 0.77 pg. Chromosome counts for six species revealed a base chromosome number of x = 17. Callicarpa chejuensis Y. H. Chung & H. Kim, C. japonica Thunb. ‘Leucocarpa’, C. longissima Merr., and C. rubella Lindl. were confirmed as diploids (2n = 2x = 34). Cytology supported flow cytometry data that C. salicifolia and C. macrophylla GEN09-0081 were tetraploids. The two accessions of C. macrophylla included in the study were found to be of different ploidy levels. The presence of two ploidy levels among and within species indicates that polyploidization events have occurred in the genus.

scholarly journals Low variability of Orchis militaris L. in a local population in the Altay Territory, Russia: evidence from morphometrical and caryological analyses

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Yulianna G. Zaytseva ◽  
◽  
Alexandra Yu. Nabieva ◽  
Elena V. Zhmud ◽  
◽  
...  
Keyword(s):  
Genome Size ◽  
Rare Species ◽  
Local Population ◽  
Chromosome Counts ◽  
Natural Conditions ◽  
Flow Cytometric Data ◽  
Flow Cytometric ◽  
Its Regions ◽  
Long Time ◽  
First Time

Orchis militaris L. is a rare species at the territory of Russia and in many of its regions. This species has been studied for a long time, but the genome size of its representatives in natural conditions has not been studied yet. This assessment is of great importance for the development of measures for the rare species preservation in natural conditions and in the tissue culture. Chromosome counts were completed by flow cytometric data and morphological observations in order to study the species intrapopulation variability. Here, the flow cytometric data on genome size and DNA content of O. militaris from the Asian part of Russia are presented for the first time.

Period of harvest, sprouting ability of cuttings, and in vitro plant regeneration in Fraxinus excelsior

1994 ◽  
Vol 72 (2) ◽  
pp. 261-267 ◽  
Author(s):  
Conceição Eneida Silveira ◽  
Alain Cottignies
Keyword(s):  
Chromosome Number ◽  
In Vitro Culture ◽  
Adventitious Roots ◽  
Woody Plant ◽  
Fraxinus Excelsior ◽  
Stem Cuttings ◽  
Natural Conditions ◽  
Apical Bud ◽  
Woody Plant Medium

Propagation by stem cuttings and in vitro culture of apical bud explants were studied on Fraxinus excelsior L. Stem cuttings from 4- to 7-year-old trees growing under natural conditions sprouted only when cuttings were taken from dormant material. Only 6% of those that had sprouted developed roots by the 7th month of culture. Similarly, only apical bud explants harvested during the dormant period sprouted in vitro. Up to 87% of these sprouts developed two to four branching adventitious roots after 5 months of culture. During the initial phase of in vitro culture, the Quoirin and Lepoivre medium and the woody plant medium favoured sprout lengthening. During the phase of multiplication, up to three sprouts per explant developed with the woody plant medium in the presence of a combination of high 6-benzylaminopurine (3.0–4.0 mg∙L−1) and low indole-3-butyric acid (0.01–0.03 mg∙L−1) concentrations. Rooting was obtained in a medium without any growth regulators. Microscopic analysis showed a direct connection between the vascular elements of adventitious roots and stem of plantlet. Chromosome number in root apices of ash plantlets and ash trees grown under natural conditions was 2n = 46. Key words: chromosome number, Fraxinus excelsior L., in vitro plants, micropropagation, stem cuttings.

scholarly journals Genome size versus geographic range size in birds

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10868
Author(s):  
Beata Grzywacz ◽  
Piotr Skórka
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Genome Size ◽  
Body Mass ◽  
Generalized Least Squares ◽  
Geographic Range ◽  
Range Size ◽  
Geographic Ranges ◽  
Brain Mass ◽  
Terrestrial Vertebrates

Why do some species occur in small, restricted areas, while others are distributed globally? Environmental heterogeneity increases with area and so does the number of species. Hence, diverse biotic and abiotic conditions across large ranges may lead to specific adaptations that are often linked to a species’ genome size and chromosome number. Therefore, a positive association between genome size and geographic range is anticipated. Moreover, high cognitive ability in organisms would be favored by natural selection to cope with the dynamic conditions within large geographic ranges. Here, we tested these hypotheses in birds—the most mobile terrestrial vertebrates—and accounted for the effects of various confounding variables, such as body mass, relative brain mass, and geographic latitude. Using phylogenetic generalized least squares and phylogenetic confirmatory path analysis, we demonstrated that range size is positively associated with bird genome size but probably not with chromosome number. Moreover, relative brain mass had no effect on range size, whereas body mass had a possible weak and negative effect, and range size was larger at higher geographic latitudes. However, our models did not fully explain the overall variation in range size. Hence, natural selection may impose larger genomes in birds with larger geographic ranges, although there may be additional explanations for this phenomenon.

Evidence of high self-fertilization in natural populations of eastern white cedar (Thuja occidentalis)

1990 ◽  
Vol 68 (3) ◽  
pp. 663-668 ◽  
Author(s):  
Daniel J. Perry ◽  
Peggy Knowles
Keyword(s):  
Natural Populations ◽  
Outcrossing Rate ◽  
Significant Heterogeneity ◽  
Embryo Survival ◽  
Thuja Occidentalis ◽  
White Cedar ◽  
Northwestern Ontario ◽  
Outcrossing Rates ◽  
Self Fertilization ◽  
Eastern White Cedar

Arrays of open-pollinated seeds were assayed for allozyme polymorphisms at four loci (Mdh-1, Me, 6Pg-2, and Pgm) to obtain estimates of outcrossing rates for three eastern white cedar populations in northwestern Ontario, Canada. Multilocus population outcrossing rate estimates were low, ranging from 0.507 to 0.745, with significant heterogeneity among populations. Low stand densities and relatively high selfed embryo survival may have contributed to the low effective outcrossing rates observed. Single-tree multilocus outcrossing rate estimates were obtained for nine trees from one population. When estimated jointly with outcross pollen pool allele frequencies, these outcrossing rate estimates ranged from 0.253 to 1.023 with significant heterogeneity among trees. Key words: mating system, outcrossing rate, Thuja occidentalis L.

Cytogenetic studies of leafy spurge, Euphorbia esula, and its allies (Euphorbiaceae)

1988 ◽  
Vol 66 (11) ◽  
pp. 2247-2257 ◽  
Author(s):  
A. E. Stahevitch ◽  
C. W. Crompton ◽  
W. A. Wojtas
Keyword(s):  
Seed Germination ◽  
Chromosome Number ◽  
Natural Populations ◽  
Leafy Spurge ◽  
Euphorbia Esula ◽  
Meiotic Abnormalities ◽  
Stability Studies ◽  
Polymorphic Species ◽  
Cytogenetic Studies ◽  
Euphorbia Cyparissias

Cytological and cytogenetic studies were carried out on populations of leafy spurge (Euphorbia esula L. s.l.) and its allies primarily from North America but also from Europe. Chromosome numbers were determined for 126 samples of E. esula, 11 of E. cyparissias L., 1 of the hybrid (E. ×pseudoesula Schur) between these two species, and 1 of E. agraria Bieb. All plants of E. esula were hexaploid. Of the total, 125 leafy spurge accessions had a chromosome number of n = 30; 1 of n = 25++. Very few meiotic abnormalities were observed. Euphorbia cyparissias was primarily tetraploid (n = 20), although occasional diploids (n = 10) were encountered. Tetraploids were fertile; diploids were sterile. The hybrid between the two foregoing species had a chromosome number of n = 25, indicating that the E. cyparissias parent was a tetraploid; meiosis in the hybrid was abnormal. Euphorbia agraria was found to have a gametic number of n = 20, which is the first chromosome number determination for this species; meiosis was normal. Artificial crosses were made successfully between 31 accessions of leafy spurge. Seed germination of the F1 progeny slightly exceeded that reported for natural populations, and meiosis was normal. Pollen stability studies were carried out on herbarium material. Stainability was 100% for most of the samples studied. Extensive pollen size polymorphism was found. It is suggested that this phenomenon supports the hypothesis that E. esula is of allopolyploid origin. No cytological or cytogenetic basis was found for considering the leafy spurge accessions examined in this study as other than as a single, albeit somewhat polymorphic, species.

scholarly journals Ploidy, Relative Genome Size, and Inheritance of Spotted Foliage in Aucuba Species (Garryaceae)

HortScience ◽  
2018 ◽  
Vol 53 (9) ◽  
pp. 1271-1274
Author(s):  
Thomas G. Ranney ◽  
Tracy H. Thomasson ◽  
Kristin Neill ◽  
Nathan P. Lynch ◽  
Mark Weathington
Keyword(s):  
Flow Cytometry ◽  
Genome Size ◽  
Ploidy Level ◽  
Nuclear Gene ◽  
Discrete Groups ◽  
Basic Information ◽  
Chromosome Counts ◽  
Leaf Trait ◽  
Leaf Variegation ◽  
Evergreen Shrubs

Aucuba have been cultivated for centuries and are valued as adaptable, broad-leaved, evergreen shrubs that also can have attractive, spotted variegations on the foliage. Improved understanding of the cytogenetics and heritability of specific traits, for specific clones and cultivars, can provide basic information to help facilitate the breeding and improvement of aucuba. The objectives of this study were to determine ploidy level and relative genome size of a diverse collection of species and cultivars of aucuba using flow cytometry and cytology and to make additional observations on heritability of spotted leaf variegation. Chromosome counts were 2n = 2x = 16 for Aucuba chinensis (A. omeiensis), 2n = 4x = 32 for A. japonica ‘Rozannie’, and 2n = 6x = 48 for A. sp. ‘Hosoba’. Relative 2C genome size for the 57 taxa varied from 13.8 pg for A. obcordata to 42.0 pg for A. ‘Hosoba’ and fell within three discrete groups consistent with cytotype. Genome size for diploid taxa (A. chinensis and A. obcordata) ranged from 13.8 to 21.0 pg, tetraploids (A. himalaica var. oblanceolata, A. japonica, and A. japonica var. borealis) ranged from 28.8 to 31.2 pg, and the first-ever reported hexaploids (A. ‘Hosoba’ and A. sp. – Vietnam) ranged from 40.5 to 42.0 pg. Unlike prior reports that indicated inheritance of spotted variegations were extranuclear genes that were maternally inherited, we found that the spotted leaf trait expressed in A. japonica ‘Shilpot’ appears to be a nuclear gene that is inherited in a quantitative fashion and not strictly maternal. These data provide an enhanced foundation for breeding improved aucuba.

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