M. Cristina Acosta

Karyotype analysis in several South American species of Solanum and Lycianthes rantonnei (Solanaceae)

Somatic chromosomes of 17 species belonging to 4 subgenera and 7 sections of Solanum and Lycianthes rantonnei are studied. All taxa have 2n = 24. The chromosome numbers of S. tripartitum, S. tenuispinum, and S. vaillantiiare reported for the first time, and the karyotype analysis of L. rantonnei is the first one for the genus. Morphometric chromosome analyses bring estimates of karyotype composition and asymmetry. In general, karyotypes are symmetrical with the chromosomes smaller than 4 μm long, being metacentric (69%), sub-metacentric (24%), or more rarely subtelocentric (7%). Solanum tucumanense, S. palinacanthum, and Solanum sp. (Acanthophora) are unique by having mostly sm and st chromosomes. All species have nucleolar organizing regions and attached satellites of variable size on short arms of one chromosome pair, usually sm or st. All species can be cytologically distinguished. Karyotype data do not allow separation of L. rantonnei from species of Solanum. Results support the validity of S. tucumanense with respect to S. pseudocapsicum. Using chromosome data exclusively, cluster analysis in 10 species from Solanum subgen. Leptostemonum reinforce the systematic arrangement of taxa in subsections based on morphological features. Because of its increased karyotype asymmetry, section Acanthophora appears to be an advanced taxon within subgen. Leptostemonum.

Phylogeny and Character Evolution in Nierembergia (Solanaceae): Molecular, Morphological, and Cytogenetic Evidence

Abstract Nierembergia (Solanaceae) contains 21 species found primarily in South America, with one species occurring disjunctly in Mexico. Among other features, a pollination system not found elsewhere in the Solanaceae typifies this genus. In most species, nectaries are absent, but oil-producing elaiophores are present on the corolla limb and these attract oil-collecting bees. Molecular phylogenetic hypotheses based on nuclear ITS and chloroplast rpl16 intron data support the monophyly of Nierembergia, which is sister to a clade composed of Bouchetia plus Hunzikeria. The data reconstruct two clades within the genus: one composed primarily of herbaceous species with broad stigmas and the second containing woody species with crescent-shaped stigmas. Morphological homoplasy is frequent among the species of the herbaceous clade, while the woody clade is morphologically cohesive. Chromosome counts are confirmed and karyotype features are given for 13 Nierembergia species (including six varieties) and for Bouchetia anomala, Leptoglossis linifolia, and Petunia axillaris. The two clades are also supported by karyotypic features: one has asymmetrical karyotypes, small chromosomes, and two chromosome pairs with nucleolar organizing regions (NOR) and the other has symmetrical karyotypes, large chromosomes, and only one NOR.

Predominant regeneration strategy results in species-specific genetic patterns in sympatric Nothofagus s.s. congeners (Nothofagaceae)

Life-history traits affect plant performance. Predominant regeneration modes, sprouting v. non-sprouting, will result in contrasting evolutionary and ecological responses that may be traced by nuclear markers. Sympatric Nothofagus Blume species provide the natural setting to test whether sprouters have a greater ability to maintain genetic diversity. In total, 28 populations along the entire distribution range of N. antarctica (G. Forst.) Oerst. were screened by eight polymorphic isozyme loci. We compared pairwise genetic patterns of the predominant sprouter N. antarctica with the mainly non-sprouter N. pumilio (Poepp. & Endl.) Krasser at 20 sympatric locations along their geographically concordant widespread range. Overall, the sprouter N. antarctica showed higher genetic variation throughout its range than did the non-sprouter N. pumilio. Mid-latitude populations of N. antarctica have maintained isozyme diversity, as inferred using genetic-landscape analysis. Despite the potential for inter-specific gene flow and past hybridisations, species identity was preserved by divergent selective forces acting on sympatric populations with distinct autoecological traits. Predominantly sprouting, as compared with mainly non-sprouting, has favoured long-term persistence of genet diversity in relatively large populations that were probably less affected by drift through time, thereby preserving molecular variants along its range. These variants, in combination with plasticity in diverse habitats, have resulted in greater resilience of N. antarctica under changing scenarios.

CHROMOSOME REPORTS IN SOUTH AMERICAN NICOTIANEAE (SOLANACEAE), WITH PARTICULAR REFERENCE TO NIEREMBERGIA1,2

Abstract Chromosome counts and karyotype information from 41 populations of 20 species and 6 varieties of Nicotianeae (Solanaceae) from South America belonging to Bouchetia Dunal (x  =  8), Fabiana Ruiz & Pav. (x  =  9), Leptoglossis Benth. (x  =  10), Nierembergia Ruiz & Pav. (x  =  8, 9), and Petunia Juss. (x  =  7, 9) are given, including first reports from 14 taxa: F. densa Rémy, N. ericoides Miers, and P. patagonica (Speg.) Millán, with 2n  =  2x  =  18, and N. browallioides Griseb., N. calycina Hook., N. graveolens A. St.-Hil., N. linariifolia Graham var. glabriuscula (Dunal) A. A. Cocucci & Hunz., var. pampeana (Millán) A. A. Cocucci & Hunz., and var. pinifolioides (Millán) A. A. Cocucci & Hunz., N. pulchella Miers var. pulchella and var. macrocalyx (Millán) A. A. Cocucci & Hunz., N. rivularis Miers, N. tucumanensis Millán, and N. veitchii Hook., with 2n  =  2x  =  16. All species studied are diploids, and most have 2n  =  16. In addition, infraspecific polyploidy is recorded for the first time in N. rigida Miers (2n  =  4x  =  32) and confirmed in N. aristata D. Don (n  =  3x  =  24, 2n  =  6x  =  48). In general, karyotypes of the examined species are symmetrical and composed of comparatively small and uniformly sized chromosomes, mostly of the metacentric (m) type except in L. linifolia (Miers) Griseb., P. axillaris (Lam.) Britton, Stern & Poggenb., and P. patagonica, where submetacentric (sm) chromosomes are predominant. There are one or, rarely, two chromosomes bearing nucleolar organizing regions per basic complement. In Nierembergia, karyotype data reflect species grouping. Results suggest that Bouchetia is the closest taxon to Nierembergia, while Leptoglossis, Petunia, and Fabiana appear more distant. Possible chromosome number evolution in the tribe is speculated based on molecular phylogenetic studies by other authors. In Nierembergia, x  =  9 is proposed to be derived from x  =  8. Dysploid changes in chromosome number and conservation of chromosome morphology in the karyotypes appear as important evolutionary events in the tribe, while polyploidy is noteworthy only in Nicotiana L.

Variación genética en Nothofagus (subgénero Nothofagus)

El subgenero Nothofagus consiste de cinco especies lenosas que estan presentes en diversas asociaciones forestales de los bosques templados de Argentina y Chile. Dadas las variaciones del medio fisico se esperan variaciones intraespecificas estructurales y funcionales con base genetica. El analisis del acervo genetico de multiples poblaciones de las distintas especies a escala regional, mediante marcadores nucleares y citoplasmaticos con baja tasa de mutacion, permitio resolver las relaciones filogeneticas y reconstruir su historia biogeografica en Patagonia, respectivamente. Secuencias nucleares ITS mostraron que N. pumilio divergio tempranamente y que N. antarctica resulto ser hermana del grupo monofiletico conteniendo las tres especies siempreverdes (N. betuloides, N. dombeyi y N. nitida). Analisis filogeograficos mediante secuencias de ADN del cloroplasto reconstruyeron rasgos antiguos del paisaje del Oligoceno-Mioceno de Patagonia y develaron la existencia de paleohibridaciones. La senal contemporanea provista por polimorfismos isoenzimaticos contribuyo al analisis de patrones espaciales de variacion como el efecto del rango geografico, la formacion de clines y ecotipos, las consecuencias geneticas de los disturbios naturales en relacion con el modo predominante de regeneracion (rebrotante y no-rebrotante) y la hibridacion. Estudios en distintos ambientes habitados por N. antarctica y experimentales en jardin comun y trasplantes reciprocos de N. pumilio en alturas contrastantes, mostraron que caracteres ecofisiologicos y morfologicos de los individuos son el resultado de seleccion natural y plasticidad. Las especies del subgenero Nothofagus son linajes antiguos que han desarrollado adaptaciones a lo largo de su historia evolutiva y, por lo tanto, tendrian el potencial de responder a cambios en el clima.

Characterization of eight species of Aloe (Asphodelaceae) from the nucleolar organizing region

Fil: Sanchez, Ysbelia. Universidad Nacional Experimental del Tachira; Venezuela. Universidad Pedagogica Experimental Libertador, Institute Pedagogico de Caracas; Venezuela