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Genome size variation and species relationships in Hieracium sub-genus Pilosella (Asteraceae) as inferred by flow cytometry.
Ann Bot 2007; 100(6):1323-35AB

Abstract

BACKGROUND AND AIMS

Hieracium sub-genus Pilosella (hawkweeds) is a taxonomically complicated group of vascular plants, the structure of which is substantially influenced by frequent interspecific hybridization and polyploidization. Two kinds of species, 'basic' and 'intermediate' (i.e. hybridogenous), are usually recognized. In this study, genome size variation was investigated in a representative set of Central European hawkweeds in order to assess the value of such a data set for species delineation and inference of evolutionary relationships.

METHODS

Holoploid and monoploid genome sizes (C- and Cx-values) were determined using propidium iodide flow cytometry for 376 homogeneously cultivated individuals of Hieracium sub-genus Pilosella, including 24 species (271 individuals), five recent natural hybrids (seven individuals) and experimental F(1) hybrids from four parental combinations (98 individuals). Chromosome counts were available for more than half of the plant accessions. Base composition (proportion of AT/GC bases) was cytometrically estimated in 73 individuals.

KEY RESULTS

Seven different ploidy levels (2x-8x) were detected, with intraspecific ploidy polymorphism (up to four different cytotypes) occurring in 11 wild species. Mean 2C-values varied approx. 4.3-fold from 3.53 pg in diploid H. hoppeanum to 15.30 pg in octoploid H. brachiatum. 1Cx-values ranged from 1.72 pg in H. pilosella to 2.16 pg in H. echioides (1.26-fold). The DNA content of (high) polyploids was usually proportional to the DNA values of their diploid/low polyploid counterparts, indicating lack of processes altering genome size (i.e. genome down-sizing). Most species showed constant nuclear DNA amounts, exceptions being three hybridogenous taxa, in which introgressive hybridization was suggested as a presumable trigger for genome size variation. Monoploid genome sizes of hybridogenous species were always between the corresponding values of their putative parents. In addition, there was a good congruency between actual DNA estimates and theoretical values inferred from putative parental combinations and between DNA values of experimental F(1) hybrids and corresponding established hybridogenous taxa.

CONCLUSIONS

Significant differences in genome size between hawkweed species from hybridogenous lineages involving the small-genome H. pilosella document the usefulness of nuclear DNA content as a supportive marker for reliable delineation of several of the most problematic taxa in Hieracium sub-genus Pilosella (including classification of borderline morphotypes). In addition, genome size data were shown to have a good predictive value for inferring evolutionary relationships and genome constitution (i.e. putative parental combinations) in hybridogenous species.

Authors+Show Affiliations

Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-128 01 Prague, Czech Republic. suda@natur.cuni.czNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17921526

Citation

Suda, Jan, et al. "Genome Size Variation and Species Relationships in Hieracium Sub-genus Pilosella (Asteraceae) as Inferred By Flow Cytometry." Annals of Botany, vol. 100, no. 6, 2007, pp. 1323-35.
Suda J, Krahulcová A, Trávnícek P, et al. Genome size variation and species relationships in Hieracium sub-genus Pilosella (Asteraceae) as inferred by flow cytometry. Ann Bot. 2007;100(6):1323-35.
Suda, J., Krahulcová, A., Trávnícek, P., Rosenbaumová, R., Peckert, T., & Krahulec, F. (2007). Genome size variation and species relationships in Hieracium sub-genus Pilosella (Asteraceae) as inferred by flow cytometry. Annals of Botany, 100(6), pp. 1323-35.
Suda J, et al. Genome Size Variation and Species Relationships in Hieracium Sub-genus Pilosella (Asteraceae) as Inferred By Flow Cytometry. Ann Bot. 2007;100(6):1323-35. PubMed PMID: 17921526.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Genome size variation and species relationships in Hieracium sub-genus Pilosella (Asteraceae) as inferred by flow cytometry. AU - Suda,Jan, AU - Krahulcová,Anna, AU - Trávnícek,Pavel, AU - Rosenbaumová,Radka, AU - Peckert,Tomás, AU - Krahulec,Frantisek, Y1 - 2007/10/07/ PY - 2007/10/9/pubmed PY - 2008/1/23/medline PY - 2007/10/9/entrez SP - 1323 EP - 35 JF - Annals of botany JO - Ann. Bot. VL - 100 IS - 6 N2 - BACKGROUND AND AIMS: Hieracium sub-genus Pilosella (hawkweeds) is a taxonomically complicated group of vascular plants, the structure of which is substantially influenced by frequent interspecific hybridization and polyploidization. Two kinds of species, 'basic' and 'intermediate' (i.e. hybridogenous), are usually recognized. In this study, genome size variation was investigated in a representative set of Central European hawkweeds in order to assess the value of such a data set for species delineation and inference of evolutionary relationships. METHODS: Holoploid and monoploid genome sizes (C- and Cx-values) were determined using propidium iodide flow cytometry for 376 homogeneously cultivated individuals of Hieracium sub-genus Pilosella, including 24 species (271 individuals), five recent natural hybrids (seven individuals) and experimental F(1) hybrids from four parental combinations (98 individuals). Chromosome counts were available for more than half of the plant accessions. Base composition (proportion of AT/GC bases) was cytometrically estimated in 73 individuals. KEY RESULTS: Seven different ploidy levels (2x-8x) were detected, with intraspecific ploidy polymorphism (up to four different cytotypes) occurring in 11 wild species. Mean 2C-values varied approx. 4.3-fold from 3.53 pg in diploid H. hoppeanum to 15.30 pg in octoploid H. brachiatum. 1Cx-values ranged from 1.72 pg in H. pilosella to 2.16 pg in H. echioides (1.26-fold). The DNA content of (high) polyploids was usually proportional to the DNA values of their diploid/low polyploid counterparts, indicating lack of processes altering genome size (i.e. genome down-sizing). Most species showed constant nuclear DNA amounts, exceptions being three hybridogenous taxa, in which introgressive hybridization was suggested as a presumable trigger for genome size variation. Monoploid genome sizes of hybridogenous species were always between the corresponding values of their putative parents. In addition, there was a good congruency between actual DNA estimates and theoretical values inferred from putative parental combinations and between DNA values of experimental F(1) hybrids and corresponding established hybridogenous taxa. CONCLUSIONS: Significant differences in genome size between hawkweed species from hybridogenous lineages involving the small-genome H. pilosella document the usefulness of nuclear DNA content as a supportive marker for reliable delineation of several of the most problematic taxa in Hieracium sub-genus Pilosella (including classification of borderline morphotypes). In addition, genome size data were shown to have a good predictive value for inferring evolutionary relationships and genome constitution (i.e. putative parental combinations) in hybridogenous species. SN - 1095-8290 UR - https://www.unboundmedicine.com/medline/citation/17921526/Genome_size_variation_and_species_relationships_in_Hieracium_sub_genus_Pilosella__Asteraceae__as_inferred_by_flow_cytometry_ L2 - https://academic.oup.com/aob/article-lookup/doi/10.1093/aob/mcm218 DB - PRIME DP - Unbound Medicine ER -