title: Chromosome numbers and DNA content in some species ofMecardonia(Gratiolae, Plantaginaceae).
abstract: Cytogenetic characterization and determination of DNA content by flow cytometry of five species ofMecardoniaRuiz et Pavon, 1798 (Gratiolae, Plantaginaceae) was performed. This is the first study of nuclear DNA content carried out in the genus. Mitotic analysis revealed a base chromosome number x = 11 for all entities and different ploidy levels, ranging from diploid (2n = 2x = 22) to hexaploid (2n = 6x = 66). The results include the ﬁrst report of the chromosome numbers forMecardonia flagellaris(Chamisso & Schlechtendal, 1827) (2n = 22),Mecardonia grandiflora(Bentham) Pennell, 1946 (2n = 22),Mecardonia kamogawaeGreppi & Hagiwara, 2011 (2n = 66), andMecardoniasp. (2n = 44). The three ploidy levels here reported suggest that polyploidy is common inMecardoniaand appear to be an important factor in the evolution of this genus. The 2C- and 1Cx-values were also estimated in all the species. The 2C-values ranged from 1.91 to 5.29 pg. The 1Cx-values ranged from 0.88 to 1.03 pg. The general tendency indicated a decrease in the 1Cx-value with increasing ploidy level. The signiﬁcance of the results is discussed in relation to taxonomy of the genus.
authors.affiliation: Instituto de Botánica del Nordeste (UNNE-CONICET). Sargento Cabral 2131. Facultad de Ciencias Exactas, Naturales y Agrimensura (UNNE). Av. Libertad 5460. 3400. Corrientes, Argentina.
authors.forename: María M
authors.initials: MM
authors.lastname: Sosa
authors.affiliation: Instituto de Botánica del Nordeste (UNNE-CONICET). Sargento Cabral 2131. Facultad de Ciencias Exactas, Naturales y Agrimensura (UNNE). Av. Libertad 5460. 3400. Corrientes, Argentina.
authors.forename: María B
authors.initials: MB
authors.lastname: Angulo
authors.affiliation: Instituto de Floricultura, Instituto Nacional de Tecnología Agropecuaria, Hurlingham 1686, Buenos Aires, Argentina.
authors.forename: Julián A
authors.initials: JA
authors.lastname: Greppi
authors.affiliation: Instituto de Botánica del Nordeste (UNNE-CONICET). Sargento Cabral 2131. Facultad de Ciencias Exactas, Naturales y Agrimensura (UNNE). Av. Libertad 5460. 3400. Corrientes, Argentina.
authors.forename: Verónica
authors.initials: V
authors.lastname: Bugallo
keywords: DNA content; Gratiolae; chromosome number; flow cytometry; polyploidy