Ploidy level and breeding system in some populations of Pilosella (Asteraceae) in eastern and southern Slovakia

The ploidy level/breeding system was determined in following species and hybrids originating from populations of the agamic polyploid complex of Pilosella in Slovakia: P. bauhini (either sexual tetraploids or apomictic pentaploids), P. hoppeana subsp. testimonialis, P. lactucella, P. onegensis (all three taxa diploid and so supposedly sexual), P. officinarum (pentaploids, hexaploids and octoploids, all cytotypes apomictic), P. glomerata (one pentaploid, another plant hexaploid and apomictic), P. macrostolona (apomictic hexaploids), P. schultesii, (mostly tetraploid, one plant an apomictic pentaploid), P. lactucella × P. onegensis (diploid and sexual), P. lactucella × P. aurantiaca (triploid and apomictic) and P. bauhini × P. officinarum (both sexual and apomictic tetraploids, apomictic pentaploids and apomictic hexaploids). The paper provides two karyological novelties in Pilosella: (a) A new hexaploid cytotype was revealed in Pilosella glomerata; (b) The octoploid apomictic and monoclonal plants of Pilosella officinarum were grown from seeds suggesting an occurrence of fruiting octoploid maternal plant(s). Such a cytotype would represent a new highest ploidy level detected in P. officinarum in the field. The cytotypes that were attributed both to P. officinarum and to the hybrids of P. bauhini and P. officinarum differed in a within-population clonal diversity. This effect could result from a different impact of (residual) sexuality and/or a different rate of origin of particular hybrid cytotypes. All findings presented in the paper are compared with published data on Pilosella species that refer preferentially to Slovakia, but also to a broader area in Central Europe.

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