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Ilia J. Leitch - One of the best experts on this subject based on the ideXlab platform.
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Is There an Upper Limit to Genome Size
Trends in plant science, 2017Co-Authors: Oriane Hidalgo, Jaume Pellicer, Andrew R. Leitch, Maarten J. M. Christenhusz, Harald Schneider, Ilia J. LeitchAbstract:At 50-fold the Size of the human Genome (3 Gb), the staggeringly huge Genome of 147.3 Gb recently discovered in the fern Tmesipteris obliqua is comparable in Size to those of the other plant and animal record-holders (i.e., Paris japonica, a flowering plant with a Genome Size of 148.8 Gb, and Protopterus aethiopicus, a lungfish with a Genome of 130 Gb). The synthesis of available information on giant Genomes suggests that the biological limit to Genome Size expansion in eukaryotes may have been reached. We propose several explanations for why the Genomes of ferns, flowering plants, and lungfish, all of which have independently undergone dramatic increases in Genome Size through a variety of mechanisms, do not exceed 150 Gb.
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The hidden side of plant invasions: the role of Genome Size
The New phytologist, 2014Co-Authors: Jan Suda, Ilia J. Leitch, Laura A. Meyerson, Petr PyšekAbstract:'Summary' 994 I. 'Introduction' 994 II. 'Genome Size research meets invasion science: ecological, phenotypic and evolutionary consequences of variation in the amount of nuclear DNA in plants' 997 III. 'Applications of Genome Size data in species-level invasion research' 1001 IV. 'Effect of climate change on Genome Size and invasion success' 1002 V. 'Gaps in knowledge and avenues for future research: towards closer integration of Genome Size knowledge into invasion ecology' 1003 VI. 'Conclusions' 1004 'Acknowledgements' 1004 References 1005 Summary The ecological role of Genome Size in plant biology, biogeography, and morphology has garnered increasing attention as the methods and technology associated with measuring cytological characteristics have become more reliable and accessible. However, how plant Genome Size influences plant invasions and at what stage in the invasion this influence occurs have been little explored. Several large-scale analyses of published data have yielded valuable interspecific comparisons, but experimental studies that manipulate environmental factors are needed, particularly below the species level, to fully understand the role that Genome Size plays in plant invasion. In this review, we summarize the available knowledge, discuss the integration of Genome Size data into invasion research, and suggest how it can be applied to detect and manage invasive species. We also explore how global climate change could exert selective pressures on plant populations with varying Genome Sizes, thereby increasing the distribution range and invasiveness of some populations while decreasing others. Finally, we outline avenues for future research, including considerations of large-scale studies of intraspecific variation in Genome Size of invasive populations, testing the interaction of Genome Size with other factors in macroecological analyses of invasions, as well as the role this trait may play in plant–enemy interactions.
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Reconstructing relative Genome Size of vascular plants through geological time
The New phytologist, 2013Co-Authors: Barry H. Lomax, Ilia J. Leitch, Jason Hilton, Richard M. Bateman, Garland R. Upchurch, Janice A. Lake, Avery B. Cromwell, Charles A. KnightAbstract:The strong positive relationship evident between cell and Genome Size in both animals and plants forms the basis of using the Size of stomatal guard cells as a proxy to track changes in plant Genome Size through geological time. We report for the first time a taxonomic fine-scale investigation into changes in stomatal guard-cell length and use these data to infer changes in Genome Size through the evolutionary history of land plants. Our data suggest that many of the earliest land plants had exceptionally large Genome Sizes and that a predicted overall trend of increasing Genome Size within individual lineages through geological time is not supported. However, maximum Genome Size steadily increases from the Mississippian (c. 360 million yr ago (Ma)) to the present. We hypothesise that the functional relationship between stomatal Size, Genome Size and atmospheric CO2 may contribute to the dichotomy reported between preferential extinction of neopolyploids and the prevalence of palaeopolyploidy observed in DNA sequence data of extant vascular plants.
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Genome Size and the Phenotype
Plant Genome Diversity Volume 2, 2012Co-Authors: Johann Greilhuber, Ilia J. LeitchAbstract: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).)
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On the Tempo of Genome Size Evolution in Angiosperms
Journal of Botany, 2010Co-Authors: Jeremy M. Beaulieu, Stephen A. Smith, Ilia J. LeitchAbstract:Broadly sampled phylogenies have uncovered extreme deviations from a molecular clock with the rates of molecular substitution varying dramatically within/among lineages. While growth form, a proxy for life history, is strongly correlated with molecular rate heterogeneity, its influence on trait evolution has yet to be examined. Here, we explore Genome Size evolution in relation to growth form by combining recent advances in large-scale phylogeny construction with model-based phylogenetic comparative methods. We construct phylogenies for Monocotyledonae (monocots) and Fabaceae (legumes), including all species with Genome Size information, and assess whether rates of Genome Size evolution depend on growth form. We found that the rates of Genome Size evolution for woody lineages were consistently an order of magnitude slower than those of herbaceous lineages. Our findings also suggest that growth form constrains Genome Size evolution, not through consequences associated with the phenotype, but instead through the influence of life history attributes on the tempo of evolution. Consequences associated with life history now extend to genomic evolution and may shed light on the frequently observed threshold effect of Genome Size variation on higher phenotypic traits.
Elizabeth J. Walsh - One of the best experts on this subject based on the ideXlab platform.
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Genome Size and lifestyle in gnesiotrochan rotifers
Hydrobiologia, 2019Co-Authors: Patrick D. Brown, Elizabeth J. WalshAbstract:Gnesiotrochan rotifers display a variety of life styles ranging from taxa with free-swimming larval and sessile adult stages to those with motile adult stages and colonial habits. Several explanations for the C -value enigma posit that Genome Size is correlated with lifestyle. To investigate this, 13 gnesiotrochan species representing nine genera were measured by flow cytometry. Genome Sizes (1C) within Gnesiotrocha ranged from 0.05 pg ( Hexarthra mira and Hexarthra fennica ) to 0.25 pg ( Sinantherina ariprepes ). Genome Sizes varied within genera and species; e.g., the H. fennica (El Huérfano, Mexico) Genome was estimated to be 15% larger than that of H. mira and H. fennica (Keystone Wetland, TX, USA). Gnesiotrochan Genome Sizes are similar to those reported within Ploima, which range from 0.06 pg ( Brachionus rotundiformis , B. dimidiatus ) to 0.46 pg ( B. asplanchnoidis ). Within Gnesiotrocha, Genome Size was found to be significantly smaller in sessile versus motile species as well as in solitary versus colonial species. To account for phylogenetic background, linear mixed models with hierarchical taxonomic ranks showed that there is a taxonomic component underlying Genome Size. This study provides the first estimates of Genome Size within the superorder, providing a baseline for genomic and evolutionary studies within the group.
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Genome Size and lifestyle in gnesiotrochan rotifers.
Hydrobiologia, 2019Co-Authors: Patrick D. Brown, Elizabeth J. WalshAbstract:Gnesiotrochan rotifers display a variety of life styles ranging from taxa with free-swimming larval and sessile adult stages to those with motile adult stages and colonial habits. Several explanations for the C-value enigma posit that Genome Size is correlated with lifestyle. To investigate this, 13 gnesiotrochan species representing nine genera were measured by flow cytometry. Genome Sizes (1C) within Gnesiotrocha ranged from 0.05 pg (Hexarthra mira and Hexarthra fennica) to 0.25 pg (Sinantherina ariprepes). Genome Sizes varied within genera and species; e.g., the H. fennica (El Huerfano, Mexico) Genome was estimated to be 15% larger than that of H. mira and H. fennica (Keystone Wetland, TX, USA). Gnesiotrochan Genome Sizes are similar to those reported within Ploima, which range from 0.06 pg (Brachionus rotundiformis, B. dimidiatus) to 0.46 pg (B. asplanchnoidis). Within Gnesiotrocha, Genome Size was found to be significantly smaller in sessile versus motile species as well as in solitary versus colonial species. To account for phylogenetic background, linear mixed models with hierarchical taxonomic ranks showed that there is a taxonomic component underlying Genome Size. This study provides the first estimates of Genome Size within the superorder, providing a baseline for genomic and evolutionary studies within the group.
J. Spencer Johnston - One of the best experts on this subject based on the ideXlab platform.
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Genome Size Evolution Differs Between Drosophila Subgenera with Striking Differences in Male and Female Genome Size in Sophophora.
G3 (Bethesda Md.), 2019Co-Authors: Carl E. Hjelmen, Heath Blackmon, V. Renee Holmes, Crystal G. Burrus, J. Spencer JohnstonAbstract:Genome Size varies across the tree of life, with no clear correlation to organismal complexity or coding sequence, but with differences in non-coding regions. Phylogenetic methods have recently been incorporated to further disentangle this enigma, yet most of these studies have focused on widely diverged species. Few have compared patterns of Genome Size change in closely related species with known structural differences in the Genome. As a consequence, the relationship between Genome Size and differences in chromosome number or inter-sexual differences attributed to XY systems are largely unstudied. We hypotheSize that structural differences associated with chromosome number and X-Y chromosome differentiation, should result in differing rates and patterns of Genome Size change. In this study, we utilize the subgenera within the Drosophila to ask if patterns and rates of Genome Size change differ between closely related species with differences in chromosome numbers and states of the XY system. Genome Sizes for males and females of 152 species are used to answer these questions (with 92 newly added or updated estimates). While we find no relationship between chromosome number and Genome Size or chromosome number and inter-sexual differences in Genome Size, we find evidence for differing patterns of Genome Size change between the subgenera, and increasing rates of change throughout time. Estimated shifts in rates of change in sex differences in Genome Size occur more often in Sophophora and correspond to known neo-sex events.
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Genome Size Evolution within and between the Sexes.
The Journal of heredity, 2018Co-Authors: Carl E. Hjelmen, V. Renee Holmes, Margaret A. Garrett, Melissa Mynes, Elizabeth Piron, J. Spencer JohnstonAbstract:Genome Sizes are known to vary between closely related species, but the patterns behind this variation have yet to be fully understood. Although this variation has been evaluated between species and within sexes, unknown is the extent to which this variation is driven by differentiation in sex chromosomes. To address this longstanding question, we examine the mode and tempo of Genome Size evolution for a total of 87 species of Drosophilidae, estimating and updating male Genome Size values for 44 of these species. We compare the evolution of Genome Size within each sex to the evolution of the differences between the sexes. Utilizing comparative phylogenetic methods, we find that male and female Genome Size evolution is largely a neutral process, reflective of phylogenetic relatedness between species, which supports the newly proposed accordion model for Genome Size change. When similarly analyzed, the difference between the sexes due to heteromorphic sex chromosomes is a dynamic process; the male-female Genome Size difference increases with time with or without known neo-Y events or complete loss of the Y. Observed instances of rapid change match theoretical expectations and known neo-Y and Y loss events in individual species.
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Genome Size Estimation and Quantitative Cytogenetics in Insects.
Methods in molecular biology (Clifton N.J.), 2018Co-Authors: J. Spencer Johnston, Angelina Bernardini, Carl E. HjelmenAbstract:With care, it is possible using flow cytometry to create a precise and accurate estimate of the Genome Size of an insect that is useful for genomics, genetics, molecular/cell biology, or systematics. Genome Size estimation is a useful first step in a complete Genome sequencing project. The number of sequencing reads required to produce a given level of coverage depends directly upon the 1C amount of DNA per cell, while an even more critical need is an accurate 1C Genome Size estimate to compare against the final assembly. Here we present a detailed protocol to estimate Genome Size using flow cytometry. Published Genome Size estimates should be submitted to GenomeSize.com so that they are available to all.
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Genome Size and ploidy of Thysanoptera.
Insect molecular biology, 2012Co-Authors: Alana L. Jacobson, J. Spencer Johnston, Dorith Rotenberg, Anna E. Whitfield, Warren Booth, Edward L. Vargo, George G. KennedyAbstract:Flow cytometry was used to study the Genome Sizes and ploidy levels for four thrips species: Franklinothrips orizabensis Johansen (Thysanoptera: Aeolothripidae), Frankliniella occidentalis Pergande, Frankliniella fusca Hinds, and Thrips tabaci Lindeman (Thysanoptera: Thripidae). F. orizabensis males and females had 1C Genome Sizes of 426 Mb and 422 Mb, respectively. Male and female F. fusca had 1C Genome Sizes of 392 Mb and 409 Mb, whereas F. occidentalis males and females had smaller 1C Genomes that were 345 Mb and 337 Mb, respectively. Male F. orizabensis, F. occidentalis and F. fusca were haploid and females diploid. Five isofemale lines of T. tabaci, initiated from parthenogenetic, thelytokous females and collected from different locations in North Carolina, were included in this study; no males were available. One isofemale line was diploid with a Genome Size of 1C = 310 Mb, and the other four had a mean Genome Size of 1C = 482 Mb, which is consistent with evidence from microsatellite data of diploidy and polyploidy, respectively, in these same five thelytokous lines. This is the first study to produce Genome Size estimates for thysanopteran species, and report polyploidy in T. tabaci populations.
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New Genome Size estimates of 134 species of arthropods
Chromosome Research, 2011Co-Authors: Shawn Jason Hanrahan, J. Spencer JohnstonAbstract:Insect Genome Size diversity remains poorly sampled, with sparse and sporadic sampling of a few select orders and with many orders unrepresented or underrepresented in the Genome Size database. Here, we present 134 Genome Size estimates for 18 orders, including the first ever Genome Size estimates for eight orders, 38 families, 102 genera, and 131 species. Also reported here are three insect species Genome Size estimates that are corrections for unpublished Genome Size values that made it into the literature, including the smallest arthropod Genome of the two spot spider mite (1C = 91 Mb). These estimates range from 91 to 7,752 Mb and provide a broader picture of Genome Size variation within Insecta and among all Arthropods. Proposed developmental constraints for holometabolous insect Genome Sizes are supported, with the majority of the species examined falling well under the hypotheSized 1,978 Mb (2 pg) limit. The only exceptions occur in the highly diverse beetles (Coleoptera) (154
Johann Greilhuber - One of the best experts on this subject based on the ideXlab platform.
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Genome Size and the Phenotype
Plant Genome Diversity Volume 2, 2012Co-Authors: Johann Greilhuber, Ilia J. LeitchAbstract: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).)
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Nuclear Genome Size: Are we getting closer?
Cytometry Part A, 2010Co-Authors: Jaroslav Dolezel, Johann GreilhuberAbstract:Correct information on Genome Size is important in many areas of research For a long time, scientists have been struggling to understand the reason for the huge variation in eukaryotic Genome Size and its biological significance More recently, the knowledge on Genome Size has become important to structure Genome sequencing projects as their scale and cost depend on Genome Size. Despite the fact that the first estimates of Genome Size in eukaryotes were made more than 50 years ago, we are still not quite sure about the exact Genome Size in practically all animal and plant species Moreover, different estimates continue to be published for the same species These discrepancies compromise data comparison and interpretation and point to methodological problems, which include standardization. This article assesses the current state of DNA reference standards for flow cytometry and the issues related to their calibration (C) 2010 International Society for Advancement of Cytometr
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Nuclear Genome Size: are we getting closer?
Cytometry. Part A : the journal of the International Society for Analytical Cytology, 2010Co-Authors: Jaroslav Dolezel, Johann GreilhuberAbstract:Correct information on Genome Size is important in many areas of research. For a long time, scientists have been struggling to understand the reason for the huge variation in eukaryotic Genome Size and its biological significance. More recently, the knowledge on Genome Size has become important to structure Genome sequencing projects as their scale and cost depend on Genome Size. Despite the fact that the first estimates of Genome Size in eukaryotes were made more than 50 years ago, we are still not quite sure about the exact Genome Size in practically all animal and plant species. Moreover, different estimates continue to be published for the same species. These discrepancies compromise data comparison and interpretation and point to methodological problems, which include standardization. This article assesses the current state of DNA reference standards for flow cytometry and the issues related to their calibration.
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Eukaryotic Genome Size databases
Nucleic Acids Research, 2006Co-Authors: T. Ryan Gregory, Ilia J. Leitch, Johann Greilhuber, James A. Nicol, Heidi Tamm, Bellis Kullman, Kaur Kullman, Brian G. Murray, Donald F. Kapraun, Michael D. BennettAbstract:Three independent databases of eukaryotic Genome Size information have been launched or re-released in updated form since 2005: the Plant DNA C-values Database (www.kew.org/GenomeSize/homepage.html), the Animal Genome Size Database (www.GenomeSize.com) and the Fungal Genome Size Database (www.zbi.ee/fungal-GenomeSize/). In total, these databases provide freely accessible Genome Size data for >10 000 species of eukaryotes assembled from more than 50 years' worth of literature. Such data are of significant importance to the genomics and broader scientific community as fundamental features of Genome structure, for genomics-based comparative biodiversity studies, and as direct estimators of the cost of complete sequencing programs.
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Genome Size in wild Pisum species.
Theoretical and Applied Genetics, 1996Co-Authors: M. Baranyi, Johann Greilhuber, W. K. SwięcickiAbstract:Genome Size was measured in 75 samples of the wild pea species Pisum abyssinicum, P. elatius, P. fulvum and P. humile by ethidium-bromide (EB) flow cytometry (internal standard: Triticum monococcum) and Feulgen densitometry (internal standard: Pisum sativum ‘Kleine Rheinlanderin’). Total variation of EB-DNA between samples covered 97.7% to 114.9% of the P. sativum value, and Feulgen DNA values were strongly correlated with EB-DNA values (r=0.9317, P < 0.001). Only P. fulvum was homogeneous in Genome Size (108.9% of P. sativum). Wide variation was observed between samples in P. abyssinicum (100.9–109.7%), P. elatius (97.7–114.9%) and P. humile (98.3–111.1% of P. sativum). In view of the world-wide Genome Size constancy in P. sativum, the present data are interpreted to show that the pea taxa with variable Genome Size are genetically inhomogeneous and that the current classification is not sufficient to describe the biological species groups adequately.
A. Lane Rayburn - One of the best experts on this subject based on the ideXlab platform.
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Genome Size of Three Miscanthus Species
Plant Molecular Biology Reporter, 2008Co-Authors: A. Lane Rayburn, Joseph Crawford, Charlotte M. Rayburn, John A. JuvikAbstract:Environmental and economic factors have stimulated research in the area of bioenergy crops. While many plants have been identified as potential energy crops, one species in particular, Miscanthus x giganteus , appears to have the most promise. As researchers attempt to exploit and improve M. x giganteus , Genome information is critical. In this study, the Genome Size of M. x giganteus and its two progenitor species were examined by flow cytometry and stomatal cell analyses. M. x giganteus was found to have Genome Size of 7.0 pg while Miscanthus sinensis and Miscanthus sacchariflorus were observed to have Genome Sizes of 5.5 and 4.5 pg respectively with stomatal Size correlating with Genome Size. Upon computing the two tetraploid × diploid hybrids theoretical Genome Sizes, the data presented in this paper supports the hypothesis of the union of a 2x M. sacchariflorus and a 1x M. sinensis gamete for the formation of the allotriploid, M. x giganteus . Such genomic information provides basic knowledge that is important in M. x giganteus plant improvement.
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Intraspecific Genome Size Variation in Pumpkin (Cucurbita pepo subsp. pepo)
HortScience, 2008Co-Authors: A. Lane Rayburn, Mosbah M. Kushad, Wanisari WannaratAbstract:Genome Size has recently been reported to vary 16% in pumpkins (Cucurbita spp.). The majority of this variation can be attributed to Genome Size differences in pumpkins of various taxonomical classes. The purpose of this study was to determine if intraspecific Genome Size variability could be detected by flow cytometry in Cucurbita pepo subsp. pepo pumpkin cultivars with similar fruit morphology. The pie pumpkins group was chosen for this study because of their similar fruit Size, shape, and color. Genome Sizes ranged from 1.109 pg in Spooktacular to 1.064 pg in Small Sugar. Spooktacular had a Genome Size larger than Small Sugar in all three experiments. Therefore, intraspecific Genome Size variation does exist in C. pepo subsp. pepo among pumpkin cultivars of similar fruit morphology.
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Genome Size variation in pumpkin (Cucurbita sp.)
Annals of Applied Biology, 2006Co-Authors: T.c. Tatum, Mosbah M. Kushad, L. Nunez, A. Lane RayburnAbstract:Pumpkins, a subgroup of the domesticated Cucurbita species, have been reported to range in fruit type (related to Size) from miniature ( 273 kg). In order to obtain a wide range of fruit types it is hypothesised that all potential factors affecting fruit type must be used. One factor that is often overlooked in plant studies is Genome Size. In various plant species, Genome Size variation has been associated with characteristics such as cell Size, plant Size and flowering time. Such characteristics are referred to as nucleotypic parameters. In order to determine if nucleotypic selection is occurring in pumpkin, 17 varieties were analysed for Genome Size variation in two separate experiments. The species selected encompass the total range of fruit types reported in pumpkin. Significant nuclear DNA content variation was observed in pumpkin. There was no significant correlation between Genome Size and fruit type. In fact, the miniature pumpkin types were found to have the same Genome Size as the jumbo pumpkin types. In addition, a positive correlation between Genome Size and stomata length (an estimate of cell Size in plants) was observed. Both the miniature and jumbo types were observed to have the smallest Genome Size and the smallest cell Size. Thus, nucleotypic selection does appear to occur in pumpkin and appears to be involved in determining fruit type, although it may not be the only factor involved.
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Documenting Intraspecfic Genome Size Variation in Soybean
Crop Science, 2004Co-Authors: A. Lane Rayburn, D. P. Biradar, Randall L. Nelson, R. Mccloskey, Kathleen M. YeaterAbstract:Reports of Genome Size variation in soybean [Glycine max (L.) Merr.] have ranged from 40 to 0%. This wide range has resulted in doubts of the existence of intraspecific DNA variation in soybean. Eighteen soybean lines were analyzed by flow cytometry to determine their Genome Size. The lines were selected on the basis of diversity of origin. Intraspecific Genome Size variation was observed at approximately 4%. To ensure that the variation observed was reproducible and not due to technique error, the two highest and lowest Genomes Size accessions were reanalyzed. The order and variation observed between the high and low Genome Size accessions were maintained. To ensure further that the differences were reproducible, seeds from the two highest and lowest Genome Size accessions were planted in different locations in the USA, grown to maturity, harvested, and the seeds returned to Illinois. The harvested seed was analyzed and again the order and variation in Genome Size between the high and low Genome Size accessions were similar to the previous two analyses even though more than 1 yr had passed between the analysis. In addition, two experiments using Amaranthus palmeri S. Wats as an internal standard were conducted. In both of these experiments, the observed variation between the previously reported high and low Genome Size soybean lines was approximately 1 to 2%. The variation between the high and low Genome Size soybean lines is reproducible. The variation reported here indicates that the DNA amount variation is between I and 4%, lower than was originally reported.