scholarly journals Interspecific Genome Size and Chromosome Number Variation Shed New Light on Species Classification and Evolution in Caladium

2014 ◽  
Vol 139 (4) ◽  
pp. 449-459 ◽  
Author(s):  
Zhe Cao ◽  
Zhanao Deng ◽  
Mike Mclaughlin

The genus Caladium Vent. is a member of the family Araceae; some of its species are cultivated as ornamentals. The present study was conducted to determine the genome size, somatic chromosome number, and their variation within 63 accessions representing 10 species of Caladium. Caladium genome sizes estimated using propidium iodide staining and flow cytometry ranged from 2.98 pg/2C in Caladium lindenii Engl. to 9.89 pg/2C in Caladium ×hortulanum Birdsey ‘Chang Suek’. Two genome size groups (large and small) were evident among the 63 caladium accessions. The average genome size of 36 caladium accessions in the large genome size group was 9.29 pg/2C, roughly twice that of the 27 accessions in the small genome size group (4.50 pg/2C). Microscopic examination of squashed root tip cells revealed seven somatic chromosome numbers among 39 caladium accessions, including 2n = 18, 20, 24, 26, 30, 34, and 38, and provided the first chromosome counts for four caladium species new to Caladium. The results support the species status of C. marmoratum Mathieu ex K. Koch, C. picturatum K. Koch & C.D. Bouché, and C. steudneriifolium Engl. that were merged into C. bicolor (Aiton) Vent. previously and also support the species status of C. clavatum Hett., Bogner & J. Boos, and C. praetermissum Bogner & Hett., two species recently established in or transferred to Caladium. The results suggest that C. bicolor and C. schomburgkii Schott, not C. picturatum or C. marmoratum, are the chief parents of the fancy-leaved caladium (C. ×hortulanum). Four caladium cytotype groups (CCG-1 to -4) were identified in scatterplot of chromosome number vs. genome size. The genome size of C. bicolor, C. schomburgkii, and C. ×hortulanum in the CCG-4 is approximately twice that of C. humboldtii (Raf.) Schott and C. picturatum in the CCG-2, and the chromosome number of C. clavatum and C. marmoratum in the CCG-3 is close to twice that of C. humboldtii and C. picturatum in the CCG-2, both suggesting possible genome duplication or tetraploidization events in Caladium. However, the chromosome number of the CCG-4 species does not correspond to an expected 2n = 36 or 40, and the genome size of the CCG-3 species does not correspond to an expected 8.98 pg/2C. Conflicts between genome size and chromosome number indicate that genome duplication events were likely followed by chromosome fusions/losses in the formation of CCG-4 species and DNA losses likely followed tetraploidization in the formation of the CCG-3 species. The high level of cytological diversity found within Caladium affects germplasm collection and preservation efforts as well as breeding programs in the genus.

2020 ◽  
Author(s):  
Jonna Sofia Eriksson ◽  
Christine D. Bacon ◽  
Dominic J. Bennett ◽  
Bernard E. Pfeil ◽  
Bengt Oxelman ◽  
...  

Abstract Background: The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e., genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and a complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, more are likely to be found due to its diversity of chromosome numbers. To reappraise the history of whole genome duplication events, we tested a series of scenarios describing different polyploidization events.Results: Using target sequence capture, we generated 87 orthologous genes from four diploid species. We detected paralogues in >54% putative single-copy genes. 34 of these genes were selected for testing three different genome duplication scenarios using gene counting. Species of Hibiscus shared one genome duplication with H. syriacus and one whole genome duplication occurred along the branch leading to H. syriacus.Conclusions: Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult.


2020 ◽  
Author(s):  
Jonna Sofia Eriksson ◽  
Christine D. Bacon ◽  
Dominic J. Bennett ◽  
Bernard E. Pfeil ◽  
Bengt Oxelman ◽  
...  

Abstract Background: The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e., genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and an allegedly complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, as more are still likely to be found, considering its diverse background. To reappraise the group’s genomic history, we tested a series of scenarios describing different polyploidization events using previously identified duplications in Hibiscus syriacus.Results: The data showed that >54% of the single-copy genes where in fact paralogues. When testing for different genome duplication scenarios using gene count data; species of Hibiscus was shown to have shared one genome duplication with H. syriacus, -- while one whole genome duplication was contained within H. syriacus, -- to be the preferred model given the observed distribution of paralogous gene copies in Hibiscus.Conclusions: Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult.


2021 ◽  
Author(s):  
Jonna Sofia Eriksson ◽  
Christine D. Bacon ◽  
Dominic J. Bennett ◽  
Bernard E. Pfeil ◽  
Bengt Oxelman ◽  
...  

Abstract Background: The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e. genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and a complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, more are likely to be found due to its diversity of chromosome numbers. To reappraise the history of whole-genome duplication events in Hibiscus, we tested three alternative scenarios describing different polyploidization events. Results: Using target sequence capture, we designed a new probe set for Hibiscus and generated 87 orthologous genes from four diploid species. We detected paralogues in >54% putative single-copy genes. 34 of these genes were selected for testing three different genome duplication scenarios using gene counting. All species of Hibiscus sampled shared one genome duplication with H. syriacus, and one whole genome duplication occurred along the branch leading to H. syriacus. Conclusions: Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
J. S. Eriksson ◽  
C. D. Bacon ◽  
D. J. Bennett ◽  
B. E. Pfeil ◽  
B. Oxelman ◽  
...  

Abstract Background The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e. genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and a complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, more are likely to be found due to its diversity of chromosome numbers. To reappraise the history of whole-genome duplication events in Hibiscus, we tested three alternative scenarios describing different polyploidization events. Results Using target sequence capture, we designed a new probe set for Hibiscus and generated 87 orthologous genes from four diploid species. We detected paralogues in > 54% putative single-copy genes. 34 of these genes were selected for testing three different genome duplication scenarios using gene counting. All species of Hibiscus sampled shared one genome duplication with H. syriacus, and one whole genome duplication occurred along the branch leading to H. syriacus. Conclusions Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult.


2021 ◽  
Author(s):  
Jonna Sofia Eriksson ◽  
Christine D. Bacon ◽  
Dominic J. Bennett ◽  
Bernard E. Pfeil ◽  
Bengt Oxelman ◽  
...  

Abstract Background: The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e. genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and a complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, more are likely to be found due to its diversity of chromosome numbers. To reappraise the history of whole-genome duplication events in Hibiscus, we tested three alternative scenarios describing different polyploidization events. Results: Using target sequence capture, we designed a new probe set for Hibiscus and generated 87 orthologous genes from four diploid species. We detected paralogues in >54% putative single-copy genes. 34 of these genes were selected for testing three different genome duplication scenarios using gene counting. All species of Hibiscus sampled shared one genome duplication with H. syriacus, and one whole genome duplication occurred along the branch leading to H. syriacus. Conclusions: Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult.


1976 ◽  
Vol 54 (10) ◽  
pp. 1135-1139 ◽  
Author(s):  
W. Michael Dennis

Cytological studies were made on the following taxa: C. addisonii, C. filifera, C. glaucophylla, C. pitcheri, C. reticulata, C. texensis, C. versicolor, and C. viorna. All species were found to have a somatic chromosome number of 16 with a uniform karyotype consisting of five pairs of metacentric chromosomes with centromeres in the median region and three pairs of acrocentric chromosomes, two pairs with centromeres in the terminal region and one pair with centromeres in the subterminal region. These findings agree with reports of chromosome number and karyotype for other species of Clematis and suggest a marked stability of chromosome complement in the genus.


Euphytica ◽  
1975 ◽  
Vol 24 (1) ◽  
pp. 6-12 ◽  
Author(s):  
W. N. M. Van Kester ◽  
C. J. T. Spitters ◽  
L. Vosselman ◽  
J. M. M. Engels ◽  
A. C. Zeven

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10868
Author(s):  
Beata Grzywacz ◽  
Piotr Skórka

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.


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