Karyotype Variation and Evolution in Gymnosperms

Murray, B. G.

doi:10.1007/978-3-7091-1160-4_14

Cited by 26 publications

(24 citation statements)

References 88 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…table 5). Similarly, heterochromatic bands occur more frequently in the proximal region of small chromosomes [Guerra, 2000], while in chromosomes >6 μm, as in gymnosperms [Murray, 2013], there is a higher frequency of terminal or interstitial bands. It is noteworthy that the mean number of sites in karyotypes with multiple sites was similar in species with small-, medium-, and large-sized chromosomes (online suppl.…”

Section: Average Chromosome Size and Distribution Of 5s Rdna Sitesmentioning

confidence: 98%

See 1 more Smart Citation

Non-Random Distribution of 5S rDNA Sites and Its Association with 45S rDNA in Plant Chromosomes

Roa¹,

Guerra²

2015

Cytogenet Genome Res

View full text Add to dashboard Cite

5S and 45S rDNA sites are the best mapped chromosome regions in eukaryotic chromosomes. In this work, a database was built gathering information about the position and number of 5S rDNA sites in 784 plant species, aiming to identify patterns of distribution along the chromosomes and its correlation with the position of 45S rDNA sites. Data revealed that in most karyotypes (54.5%, including polyploids) two 5S rDNA sites (a single pair) are present, with 58.7% of all sites occurring in the short arm, mainly in the proximal region. In karyotypes of angiosperms with only 1 pair of sites (single sites) they are mostly found in the proximal region (52.0%), whereas in karyotypes with multiple sites the location varies according to the average chromosome size. Karyotypes with multiple sites and small chromosomes (<3 µm) often display proximal sites, while medium-sized (between 3 and 6 µm) and large chromosomes (>6 µm) more commonly show terminal or interstitial sites. In species with holokinetic chromosomes, the modal value of sites per karyotype was also 2, but they were found mainly in a terminal position. Adjacent 5S and 45S rDNA sites were often found in the short arm, reflecting the preferential distribution of both sites in this arm. The high frequency of genera with at least 1 species with adjacent 5S and 45S sites reveals that this association appeared several times during angiosperm evolution, but it has been maintained only rarely as the dominant array in plant genera.

show abstract

Section: Average Chromosome Size and Distribution Of 5s Rdna Sitesmentioning

confidence: 98%

“…fig. 1b) [Murray, 2013]. On the other hand, the number of sites per karyotype among gymnosperms ranges from 2-8, whereas among angiosperms it varies from 2-20 (online suppl.…”

Section: Number Of 5s Rdna Sites Per Karyotypementioning

confidence: 99%

Non-Random Distribution of 5S rDNA Sites and Its Association with 45S rDNA in Plant Chromosomes

Roa¹,

Guerra²

2015

Cytogenet Genome Res

View full text Add to dashboard Cite

show abstract

“…This is reminiscent of the situation in the angiosperm genus Aloe where variability in rDNA distribution within a fixed karyotype structure was also reported (Adams et al, 1998). Nevertheless, Pinus species have more numerous 45S rDNA sites than is typical of angiosperms (Murray, 2012). Indeed, Pinus taeda has 38 rDNA sites distributed across its 24 chromosomes, a likely record in plants (Fig.…”

Section: Chromosome Structure -Less Dynamic Genomes In Coniferalesmentioning

confidence: 99%

“…However, most of our understanding of gymnosperm chromosomes is derived from conifers, particularly Pinaceae, especially Pinus, and, to a lesser extent, the cycads. Here we summarize some general features (for a more extensive analysis, see Murray, 2012).…”

Section: Chromosome Structure -Less Dynamic Genomes In Coniferalesmentioning

confidence: 99%

Ecological and genetic factors linked to contrasting genome dynamics in seed plants

2012

View full text Add to dashboard Cite

SummaryThe large-scale replacement of gymnosperms by angiosperms in many ecological niches over time and the huge disparity in species numbers have led scientists to explore factors (e.g. polyploidy, developmental systems, floral evolution) that may have contributed to the astonishing rise of angiosperm diversity. Here, we explore genomic and ecological factors influencing seed plant genomes. This is timely given the recent surge in genomic data. We compare and contrast the genomic structure and evolution of angiosperms and gymnosperms and find that angiosperm genomes are more dynamic and diverse, particularly amongst the herbaceous species. Gymnosperms typically have reduced frequencies of a number of processes (e.g. polyploidy) that have shaped the genomes of other vascular plants and have alternative mechanisms to suppress genome dynamism (e.g. epigenetics and activity of transposable elements). Furthermore, the presence of several characters in angiosperms (e.g. herbaceous habit, short minimum generation time) has enabled them to exploit new niches and to be viable with small population sizes, where the power of genetic drift can outweigh that of selection. Together these processes have led to increased rates of genetic divergence and faster fixation times of variation in many angiosperms compared with gymnosperms.

show abstract

“…The frequency of polyploidy in all clades of Ephedra may point to a particular role of chromosomal speciation in arid regions. The genome of Welwitschia mirabilis , with 2n = 42 (Khoshoo & Ahuja, , ) and a 1C‐value of 7.20 pg (Leitch et al, ) also appears of polyploid origin (Khoshoo & Ahuja, ; Murray, ), which is supported by the above‐mentioned transcriptomic study (Li et al, ).…”

Section: The Gnetales: Three Disparate Monogeneric Familiesmentioning

confidence: 68%

The Gnetales: Recent insights on their morphology, reproductive biology, chromosome numbers, biogeography, and divergence times

Ickert‐Bond

Renner

2016

J of Sytematics Evolution

View full text Add to dashboard Cite

Ephedra, Gnetum, and Welwitschia constitute the gymnosperm order Gnetales of still unclear phylogenetic relationships within seed plants. Here we review progress over the past 10 years in our understanding of their species diversity, morphology, reproductive biology, chromosome numbers, and genome sizes, highlighting the unevenness in the sampling of species even for traits that can be studied in preserved material, such as pollen morphology. We include distribution maps and original illustrations of key features, and specify which species groups or geographic areas are undersampled.

show abstract

Karyotype Variation and Evolution in Gymnosperms

Cited by 26 publications

References 88 publications

Non-Random Distribution of 5S rDNA Sites and Its Association with 45S rDNA in Plant Chromosomes

Non-Random Distribution of 5S rDNA Sites and Its Association with 45S rDNA in Plant Chromosomes

Ecological and genetic factors linked to contrasting genome dynamics in seed plants

The Gnetales: Recent insights on their morphology, reproductive biology, chromosome numbers, biogeography, and divergence times

Contact Info

Product

Resources

About