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Evolutionary and Taxonomic Implications of Variation in Nuclear Genome Size: Lesson from the Grass Genus Anthoxanthum (Poaceae).

Chumová Z, Krejčíková J, Mandáková T, Suda J, Trávníček P - PLoS ONE (2015)

Bottom Line: In addition to diploids, we found two low (rare 3x and common 4x) and one high (~16x-18x) polyploid levels.Intraspecific variation in genome size was observed in all recognized species, the most striking example being the A. aristatum/ovatum complex.Altogether, our study showed that genome size can be a useful taxonomic marker in Anthoxathum to not only guide taxonomic decisions but also help resolve evolutionary relationships in this challenging grass genus.

View Article: PubMed Central - PubMed

Affiliation: Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic.

ABSTRACT
The genus Anthoxanthum (sweet vernal grass, Poaceae) represents a taxonomically intricate polyploid complex with large phenotypic variation and its evolutionary relationships still poorly resolved. In order to get insight into the geographic distribution of ploidy levels and assess the taxonomic value of genome size data, we determined C- and Cx-values in 628 plants representing all currently recognized European species collected from 197 populations in 29 European countries. The flow cytometric estimates were supplemented by conventional chromosome counts. In addition to diploids, we found two low (rare 3x and common 4x) and one high (~16x-18x) polyploid levels. Mean holoploid genome sizes ranged from 5.52 pg in diploid A. alpinum to 44.75 pg in highly polyploid A. amarum, while the size of monoploid genomes ranged from 2.75 pg in tetraploid A. alpinum to 9.19 pg in diploid A. gracile. In contrast to Central and Northern Europe, which harboured only limited cytological variation, a much more complex pattern of genome sizes was revealed in the Mediterranean, particularly in Corsica. Eight taxonomic groups that partly corresponded to traditionally recognized species were delimited based on genome size values and phenotypic variation. Whereas our data supported the merger of A. aristatum and A. ovatum, eastern Mediterranean populations traditionally referred to as diploid A. odoratum were shown to be cytologically distinct, and may represent a new taxon. Autopolyploid origin was suggested for 4x A. alpinum. In contrast, 4x A. odoratum seems to be an allopolyploid, based on the amounts of nuclear DNA. Intraspecific variation in genome size was observed in all recognized species, the most striking example being the A. aristatum/ovatum complex. Altogether, our study showed that genome size can be a useful taxonomic marker in Anthoxathum to not only guide taxonomic decisions but also help resolve evolutionary relationships in this challenging grass genus.

No MeSH data available.


Distribution of species and cytotypes of Anthoxanthum in the area studied, based on analysis of 628 individuals from 197 populations sampled in 29 European countries.
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pone.0133748.g001: Distribution of species and cytotypes of Anthoxanthum in the area studied, based on analysis of 628 individuals from 197 populations sampled in 29 European countries.

Mentions: A total of 197 Anthoxanthum populations, originating from 29 European countries were sampled during 2006–2015 (Fig 1, S1 Table). The sampling was designed to cover the entire distribution range of the genus in Europe and to include all currently recognized taxa; a major sampling effort was directed at southern Europe, which exhibits the greatest diversity [41]. At each locality, whenever possible, the following material was collected for each taxon distinguished visually: (1) flowering plants (1–17 individuals, depending on the population size) with well-developed intact leaves for FCM estimation of nuclear genome size–tissue was stored at 4°C in a plastic bag and FCM analyses were performed within a week (usually within a few days); (2) a single large tuft, for subsequent cultivation in the experimental garden of the Institute of Botany, Academy of Sciences in Průhonice, the Czech Republic (N 49°59.7´ E 14°34.0´, 315 m a.s.l.); (3) ripe caryopses from several individuals, as back-up material; (4) herbarium vouchers (deposited in the PRC).


Evolutionary and Taxonomic Implications of Variation in Nuclear Genome Size: Lesson from the Grass Genus Anthoxanthum (Poaceae).

Chumová Z, Krejčíková J, Mandáková T, Suda J, Trávníček P - PLoS ONE (2015)

Distribution of species and cytotypes of Anthoxanthum in the area studied, based on analysis of 628 individuals from 197 populations sampled in 29 European countries.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4514812&req=5

pone.0133748.g001: Distribution of species and cytotypes of Anthoxanthum in the area studied, based on analysis of 628 individuals from 197 populations sampled in 29 European countries.
Mentions: A total of 197 Anthoxanthum populations, originating from 29 European countries were sampled during 2006–2015 (Fig 1, S1 Table). The sampling was designed to cover the entire distribution range of the genus in Europe and to include all currently recognized taxa; a major sampling effort was directed at southern Europe, which exhibits the greatest diversity [41]. At each locality, whenever possible, the following material was collected for each taxon distinguished visually: (1) flowering plants (1–17 individuals, depending on the population size) with well-developed intact leaves for FCM estimation of nuclear genome size–tissue was stored at 4°C in a plastic bag and FCM analyses were performed within a week (usually within a few days); (2) a single large tuft, for subsequent cultivation in the experimental garden of the Institute of Botany, Academy of Sciences in Průhonice, the Czech Republic (N 49°59.7´ E 14°34.0´, 315 m a.s.l.); (3) ripe caryopses from several individuals, as back-up material; (4) herbarium vouchers (deposited in the PRC).

Bottom Line: In addition to diploids, we found two low (rare 3x and common 4x) and one high (~16x-18x) polyploid levels.Intraspecific variation in genome size was observed in all recognized species, the most striking example being the A. aristatum/ovatum complex.Altogether, our study showed that genome size can be a useful taxonomic marker in Anthoxathum to not only guide taxonomic decisions but also help resolve evolutionary relationships in this challenging grass genus.

View Article: PubMed Central - PubMed

Affiliation: Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic.

ABSTRACT
The genus Anthoxanthum (sweet vernal grass, Poaceae) represents a taxonomically intricate polyploid complex with large phenotypic variation and its evolutionary relationships still poorly resolved. In order to get insight into the geographic distribution of ploidy levels and assess the taxonomic value of genome size data, we determined C- and Cx-values in 628 plants representing all currently recognized European species collected from 197 populations in 29 European countries. The flow cytometric estimates were supplemented by conventional chromosome counts. In addition to diploids, we found two low (rare 3x and common 4x) and one high (~16x-18x) polyploid levels. Mean holoploid genome sizes ranged from 5.52 pg in diploid A. alpinum to 44.75 pg in highly polyploid A. amarum, while the size of monoploid genomes ranged from 2.75 pg in tetraploid A. alpinum to 9.19 pg in diploid A. gracile. In contrast to Central and Northern Europe, which harboured only limited cytological variation, a much more complex pattern of genome sizes was revealed in the Mediterranean, particularly in Corsica. Eight taxonomic groups that partly corresponded to traditionally recognized species were delimited based on genome size values and phenotypic variation. Whereas our data supported the merger of A. aristatum and A. ovatum, eastern Mediterranean populations traditionally referred to as diploid A. odoratum were shown to be cytologically distinct, and may represent a new taxon. Autopolyploid origin was suggested for 4x A. alpinum. In contrast, 4x A. odoratum seems to be an allopolyploid, based on the amounts of nuclear DNA. Intraspecific variation in genome size was observed in all recognized species, the most striking example being the A. aristatum/ovatum complex. Altogether, our study showed that genome size can be a useful taxonomic marker in Anthoxathum to not only guide taxonomic decisions but also help resolve evolutionary relationships in this challenging grass genus.

No MeSH data available.