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Genome sizes of 227 accessions of Gagea (Liliaceae) discriminate between the species from the Netherlands and reveal new ploidies in Gagea.

Zonneveld BJ, Te Linde B, van den Berg LJ - Springerplus (2015)

Bottom Line: Apart from 14 diploid G. villosa, six plants of G. villosa with an inferred tetraploidy were found.Inferred tetraploid and hexaploid G. pratensis were found in 30 and 20 localities, respectively.In one locality an inferred decaploid (10×) plant was found that could represent a doubled pentaploid G. pratensis.

View Article: PubMed Central - PubMed

Affiliation: NBC Naturalis, Herbarium Section, P.O. Box 9517, 2300 RA Leiden, The Netherlands.

ABSTRACT
Nuclear genome size, as measured by flow cytometry with propidium iodide, was used to investigate the relationships within the genus Gagea (Liliaceae), mainly from the Netherlands. The basic chromosome number for Gagea is x = 12. The inferred ploidy in the Dutch and German accessions varies from diploid to decaploid. Consequently there is a large range of genome sizes (DNA 2C-values) from 14.9 to 75.1 pg. Genome sizes are evaluated here in combination with the results of morphological observations. Five species and the hybrid G. × megapolitana are reported. Apart from 14 diploid G. villosa, six plants of G. villosa with an inferred tetraploidy were found. For the 186 Dutch accessions investigated 85 turned out to be the largely sterile G. pratensis (inferred to be pentaploid). Inferred tetraploid and hexaploid G. pratensis were found in 30 and 20 localities, respectively. In one locality an inferred decaploid (10×) plant was found that could represent a doubled pentaploid G. pratensis. An inferred decaploid G. pratensis was never reported before. The genome size of Gagea × megapolitana from Germany fitted with its origin as a cross between the two hexaploids G. pratensis and G. lutea. Gagea spathacea from the Netherlands was inferred to be nonaploid as was recorded from plants across Europe. The aim of the study was to use flow cytometry as a tool to elucidate the taxonomic position of the Dutch Gagea.

No MeSH data available.


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Gagea pratensis pentaploid (b) April 3, 2011 in Bingerden.
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Fig11: Gagea pratensis pentaploid (b) April 3, 2011 in Bingerden.

Mentions: Gagea pratensis is a glabrous plant with up to four flowers per scape. Characteristic are the two nude egglike, horizontal bulbils. Gagea pratensis can be found in The Netherlands with four different inferred ploidies. They can be recognized in that the tetraploid has the leaf sheath circling the stem halfway, the pentaploid three-quarter and the hexaploid and the decaploid completely. They are shown in Figs. 9, 10, 11, 12 and 13. The tetraploids (30 accessions) have a DNA 2C-value (nuclear DNA content) of on average 32.8 pg, the pentaploids (85 accessions) have on average 39.9 pg and the hexaploids (20 accessions) have on average 45.6 pg. The pentaploids could be hybrids between the tetraploid and the hexaploid cytotypes. Even a decaploid with 75.8 pg has been found. The pentaploid form of G. pratensis is by far the most common Gagea in The Netherlands with 39.5 pg from 85 out of 186 localities. The same ploidy is counted in all 7 populations of G. pratensis from Mecklenburg (Germany) (Henker 2005). Therefore it seems most likely that the decaploid plant is derived from the frequently found pentaploid G. pratensis that has in this case doubled its genome. As often in polyploids, DNA might have been lost and a similar loss is found in the hexaploid G. pratensis but not in the lower ploidies. The inferred decaploid plants have not been reported before for G. pratensis. Being pentaploid in most cases, it comes as no surprise that G. pratensis is considered to be sterile (van der Meijden 2005). Taxa with anorthoploid chromosome sets often show a highly irregular meiosis. An exception are large plants from Zutphen, NL that are fully fertile and differ morphologically with a large basal leaf and 4–8 flowers to a stem. They have a genome size similar to pentaploid G. pratensis, but look more like G. × megapolitana Henker (Henker 2005). Out of 50 germinated seeds, five seedlings measured from the Zutphen locality had the same genome size as their parents. This is peculiar for a pentaploid. Earlier analysis of seedlings of the triploid Hosta ‘Sum and Substance’ show different, but lower genome sizes in the seedlings (Zonneveld and Pollock 2012). Pfeiffer et al. (2013) report also that some pentaploid populations of G. pratensis are partially fertile. None of the calculated genome sizes of the possible hybrids between G. lutea and G. pratensis would fit the plants from Zutphen. Hence more research is required to explain these results.Fig. 9


Genome sizes of 227 accessions of Gagea (Liliaceae) discriminate between the species from the Netherlands and reveal new ploidies in Gagea.

Zonneveld BJ, Te Linde B, van den Berg LJ - Springerplus (2015)

Gagea pratensis pentaploid (b) April 3, 2011 in Bingerden.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4524885&req=5

Fig11: Gagea pratensis pentaploid (b) April 3, 2011 in Bingerden.
Mentions: Gagea pratensis is a glabrous plant with up to four flowers per scape. Characteristic are the two nude egglike, horizontal bulbils. Gagea pratensis can be found in The Netherlands with four different inferred ploidies. They can be recognized in that the tetraploid has the leaf sheath circling the stem halfway, the pentaploid three-quarter and the hexaploid and the decaploid completely. They are shown in Figs. 9, 10, 11, 12 and 13. The tetraploids (30 accessions) have a DNA 2C-value (nuclear DNA content) of on average 32.8 pg, the pentaploids (85 accessions) have on average 39.9 pg and the hexaploids (20 accessions) have on average 45.6 pg. The pentaploids could be hybrids between the tetraploid and the hexaploid cytotypes. Even a decaploid with 75.8 pg has been found. The pentaploid form of G. pratensis is by far the most common Gagea in The Netherlands with 39.5 pg from 85 out of 186 localities. The same ploidy is counted in all 7 populations of G. pratensis from Mecklenburg (Germany) (Henker 2005). Therefore it seems most likely that the decaploid plant is derived from the frequently found pentaploid G. pratensis that has in this case doubled its genome. As often in polyploids, DNA might have been lost and a similar loss is found in the hexaploid G. pratensis but not in the lower ploidies. The inferred decaploid plants have not been reported before for G. pratensis. Being pentaploid in most cases, it comes as no surprise that G. pratensis is considered to be sterile (van der Meijden 2005). Taxa with anorthoploid chromosome sets often show a highly irregular meiosis. An exception are large plants from Zutphen, NL that are fully fertile and differ morphologically with a large basal leaf and 4–8 flowers to a stem. They have a genome size similar to pentaploid G. pratensis, but look more like G. × megapolitana Henker (Henker 2005). Out of 50 germinated seeds, five seedlings measured from the Zutphen locality had the same genome size as their parents. This is peculiar for a pentaploid. Earlier analysis of seedlings of the triploid Hosta ‘Sum and Substance’ show different, but lower genome sizes in the seedlings (Zonneveld and Pollock 2012). Pfeiffer et al. (2013) report also that some pentaploid populations of G. pratensis are partially fertile. None of the calculated genome sizes of the possible hybrids between G. lutea and G. pratensis would fit the plants from Zutphen. Hence more research is required to explain these results.Fig. 9

Bottom Line: Apart from 14 diploid G. villosa, six plants of G. villosa with an inferred tetraploidy were found.Inferred tetraploid and hexaploid G. pratensis were found in 30 and 20 localities, respectively.In one locality an inferred decaploid (10×) plant was found that could represent a doubled pentaploid G. pratensis.

View Article: PubMed Central - PubMed

Affiliation: NBC Naturalis, Herbarium Section, P.O. Box 9517, 2300 RA Leiden, The Netherlands.

ABSTRACT
Nuclear genome size, as measured by flow cytometry with propidium iodide, was used to investigate the relationships within the genus Gagea (Liliaceae), mainly from the Netherlands. The basic chromosome number for Gagea is x = 12. The inferred ploidy in the Dutch and German accessions varies from diploid to decaploid. Consequently there is a large range of genome sizes (DNA 2C-values) from 14.9 to 75.1 pg. Genome sizes are evaluated here in combination with the results of morphological observations. Five species and the hybrid G. × megapolitana are reported. Apart from 14 diploid G. villosa, six plants of G. villosa with an inferred tetraploidy were found. For the 186 Dutch accessions investigated 85 turned out to be the largely sterile G. pratensis (inferred to be pentaploid). Inferred tetraploid and hexaploid G. pratensis were found in 30 and 20 localities, respectively. In one locality an inferred decaploid (10×) plant was found that could represent a doubled pentaploid G. pratensis. An inferred decaploid G. pratensis was never reported before. The genome size of Gagea × megapolitana from Germany fitted with its origin as a cross between the two hexaploids G. pratensis and G. lutea. Gagea spathacea from the Netherlands was inferred to be nonaploid as was recorded from plants across Europe. The aim of the study was to use flow cytometry as a tool to elucidate the taxonomic position of the Dutch Gagea.

No MeSH data available.


Related in: MedlinePlus