Franco Chiarini

Arbuscular mycorrhizal colonization of vascular plants from the Yungas forests, Argentina

In Argentina, the Yungas forests are among the ecosystems most affected by human activity, with loss of biodiversity. To assess the mycorrhizal status in these ecosystems, the roots of 41 native plant species belonging to 25 families were collected throughout the year from two sites of the Yungas forests. Roots were washed and stained to study the presence of arbuscular mycorrhizas (AM). Morphological types of arbuscular mycorrhizas (Arum and Paris-type) and colonization patterns were identified and photographed. All plants presented AM colonization. The AM colonization patterns varied from single intracellular aseptate hyphae, coils, appresoria, to vesicles and/or arbuscules. Among the species studied, the Paris-type colonization showed to be dominant. Results confirmed that AM hosts are predominant in the Yungas of South American forests.RésuméEn Argentine, les Yungas constituent un des écosystèmes les plus atteints par l’activité de l’homme, avec la perte de biodiversité qui en découle. Pour évaluer le statut mycorhizien de ces écosystèmes, les racines de 41 plantes autochtones appartenant à 25 familles ont été collectées au cours de l’année dans deux sites des forêts des Yungas. Les racines ont été lavées et teintes afin de déterminer la présence des mycorhizes arbusculaires (MA). Les types morphologiques de MA (type Arum et Paris) et les patrons de colonisation ont été identifiés et photographiés. Toutes les plantes ont présenté une colonisation MA. Les structures fongiques intraracinaires comprenaient des hyphes intracellulaires sans cloison, des boucles, des appressoria, des vésicules et/ou des arbuscules. Le type de colonisation Paris est apparu comme dominant parmi les espèces étudiées. Les résultats confirment que les hôtes avec MA prédominent dans les forêts sudaméricaines des Yungas.

Karyotypes of some species of Cestrum, Sessea, and Vestia (tribe Cestreae, Solanaceae)

Abstract The somatic chromosomes of Cestrum bigibbosum Pittier, C. buxifolium Kunth, Sessea corymbosa Goudot ex Taylor and Phillips and Vestia foetida (Ruiz et Pav.) Hoffmanns, were examined by classical staining. The number 2n = 2x = 16 was found for all species. The total genome length ranged from 57.70 to 92.09 μm and the average chromosome length from 7.21 to 11.51 μm. Karyotypes were notably symmetrical. Haploid karyotype formulae were 8 m pairs (C. bigibbosum, V. foetida) or 7 m + 1 sm pairs (S. corymbiflora, C. buxifolium). Except Sessea corymbiflora in which satellites were not visualized, the remaining species showed one satellited pair. The species can be distinguished by a combination of karyotype formula, karyotype length, and the position of satellites in a particular chromosome pair. Karyotype diversification in tribe Cestreae is suggested to have been accompanied by a tendency towards slight asymmetry and increased genome length.

Geographical pattern and ploidy levels of the weed Solanum elaeagnifolium (Solanaceae) from Argentina

A total of 106 samples taken from natural Argentinean populations of the weedy Solanum elaeagnifolium (subgenus Leptostemonum) were studied cytologically to understand the impact of the different ploidy levels in its distribution and origin. Classical Feulgen staining was employed to determine mitotic chromosome numbers in all samples. 2C nuclear DNA content was determined by means of PI flow cytometry in eight samples of different ploidy levels. Principal component analysis and GIS tools were employed to compare altitude, annual precipitation and annual mean temperature among accessions. Three cytotypes were found: diploid (2nxa0=xa024) which is widespread, tetraploid (2nxa0=xa048) centered in western and southern Argentina, and hexaploid (2nxa0=xa072) which predominates in central Argentina extending as well to the east. The annual precipitation is significantly different between tetraploids and hexaploids. Cx-values ranged from 1.231 to 1.275xa0pg, with statistical differences (of about 24.5–50.9xa0Mbp, pxa0≤xa00.05) among accessions. Diploids are the most widespread cytotype and have adapted to a number of very different habitats. Tetraploids live in arid or semi-arid regions with a mean annual rainfall less than 500xa0mm. Hexaploids are successful in colonizing wetter areas, where no tetraploids were found. Thus, the distribution of cytotypes may be associated with habitat differences, particularly soil moisture. The observed cytotype pattern and the differences in DNA content suggest multiple places of origin for the polyploidy of S. elaeagnifolium in Argentina.

A Revision of Solanum Section Lathyrocarpum (the Carolinense Clade, Solanaceae)

Abstract A new taxonomic circumscription of Solanum section Lathyrocarpum is proposed to include 11 species from North and South America. The section is placed in the cosmopolitan S. subgenus Leptostemonum, which contains 350–450 species. As defined here, S. sect. Lathyrocarpum includes all the taxa resolved in the Carolinense clade in previous molecular phylogenetic studies as well as one species not sampled in those analyses. The combination of morphological characters that define the group includes: herbaceous perennial habit with extensive root systems, often with endogenous buds that can sprout, a sparse to dense indumentum of sessile to stalked stellate hairs and tapered prickles, 2- to 3-foliate to plurifoliate sympodial units, extra-axillary inflorescences with 1–20 flowers, a weakly andromonoecious reproductive system, corollas ranging in color from white to lavender, and fruits maturing to yellow or yellowish-orange. Most species in the section have a weedy habit and grow in highly disturbed areas, but four are narrowly distributed. One species, S. carolinense, is a noxious invasive weed that has been inadvertently introduced to many areas around the world. There are a variety of ploidy levels represented in the group (n = 12, 18, 24, and 36). In this work, we present a new circumscription of the section and provide descriptions, distribution maps, preliminary IUCN conservation assessments, and a key to identify the 11 included species. We also designate lectotypes for nine names and select a neotype for S. dimidiatum.

Real Identity of Witheringia sellowiana (Solanaceae), Typification, and Chromosome Number

Abstract The identity of Witheringia sellowiana, a narrow endemic species from São Paulo (Brazil), is reconsidered. After analysis of the protologue and the morphological characters of the type material and recent flowering collections, a new combination is proposed ( Aureliana sellowiana (Sendtn.) Barboza & Stehmann). A lectotype and epitype are designated here. A detailed description and illustration, an analysis of the karyotype of A. sellowiana, and a discussion of its closest relatives are provided. A key to differentiate the species of Aureliana is also given.

Novedades en Solanum y Salpichroa (Solanaceae) para Sudamérica austral

El presente articulo tiene por objeto dar a conocer novedades en dos generos de Solanaceae: Solanum y Salpichroa. En Solanum se aclara la identidad y sinonimia de dos especies del subgen. Leptostemonum (S. bonariense y S. guaraniticum), y se reporta por primera vez la presencia de S. julocrotonoides (sect. Brevantherum) para Argentina. Para Salpichroa se documenta la presencia de este genero para la flora de Chile, con 3 taxones (S. origanifolia, S. scandens y S. tristis var. lehmannii). Todas las especies son descriptas e ilustradas.

Phylogeny of the Carolinense Clade of Solanum (Solanaceae) Inferred from Nuclear and Plastid DNA Sequences

Abstract n The large and economically important genus Solanum contains ca. 1,400 species distributed worldwide. One of the 12–14 major clades identified in the genus is the Leptostemonum clade, or tire “spiny solanums.” Previous molecular phylogenetic studies have identified 14 major clades in the spiny solanums. Among these is the Carolinense clade, which contains Solanum carolinense, the type species of S. subsect. Lathyrocarpum. However, previous results have suggested that the species composition of the Carolinense clade is only partially congruent with taxonomic circumscriptions of S. subsect. Lathyrocarpum. The main goal of this study was to increase taxon sampling over previous molecular phylogenies in order to better understand the composition of the Carolinense clade. We newly sequenced 31 accessions of 17 taxa putatively belonging to the clade for two nuclear (ITS, waxy) and one plastid gene region (trnT-trnF) and combined these with previously generated molecular data. Phylogenetic analyses of separate and combined DNA matrices were done using maximum parsimony and Bayesian methods. Results from analyses of the combined nuclear and plastid data set showed 10 taxa to be resolved within a well-supported Carolinense clade. However, three species, Solanum dimidiatum, S. perplexum, and S. hieronymi, showed conflicting placements in phylogenies based on analyses of nuclear vs. plastid data sets, suggesting a history of allopolyploidy or introgression. Within the Carolinense clade, the North and South American species were both recovered as well-supported clades, implying a single dispersal event from South to North America.

Data reassessment in a phylogenetic context gives insight into chromosome evolution in the giant genus Solanum (Solanaceae)

Chromosome data are fundamental in evolution. However, there has been no attempt to synthesize and evaluate the significance of such information from a phylogenetic perspective in the giant genus Solanum, which was the aim of this work. New and published information of the main cytotaxonomic features (chromosome number, polyploidy, total length of the haploid complement, mean chromosome length, mean arm ratio, karyotype formula, nuclear DNA amount, number/position of rDNA sites) was compiled and mapped onto an embracing Solanaceae phylogeny, performing Ancestral States Reconstruction. There were 506 Solanum species with chromosome counts (49.7% from an estimated total of 1,018 spp.), with xu2009=u200912 being the most frequent number (97%). Species with karyotypes represent 18.8%, while 8% have been studied with any molecular cytogenetic technique. Chromosome characters showed transitions associated with supported nodes, some of which have undergone fewer transitions than others. The common ancestor of all Solanum was a diploid with 2nu2009=u200924, a karyotype with st and/or t chromosomes, 2C DNA content of 1–1.2 pg, one locus of 18–5.8–26S rDNA and one of 5S, both loci being asyntenic. The chromosomal variables behave as homoplastic, with reversions in all branches. The analysed characters were sorted from more to less conserved: asynteny of rDNA loci; number of sites of 18–5.8–26S; chromosome number; karyotype formula; number of 5S loci. This pattern of chromosomal evolution distinguishes Solanum from closely related genera and from genera from other families with a similar number of species.