Population genetic structure of Sisyrinchium micranthum Cav. (Iridaceae) in Itapuã State Park, Southern Brazil

Sisyrinchium micranthum Cav. is a member of the family Iridaceae, which is distributed over the American continent. In Brazil, this species is found, not only in disturbed areas and coastal regions, but is also very common in urban centers, such as public parks, during the spring. Chromosome counts for North American specimens are 2n = 32 and 2n = 48, whereas in southern Brazil, there is a polyploidy series with three chromosome numbers, 2n = 16, 2n = 32, and 2n = 48. Population analyses using DNA molecular markers are inexistent for this species, in spite of its wide distribution and morphological variation. To study the genetic population structure of S. micranthum, five natural populations were accessed in a conservation park within the Atlantic Rain Forest Biome in southern Brazil. Here, the chromosome numbers 2n = 16 and 2n = 48 had already been described. Molecular analysis showed that the populations are highly structured with low gene flow among them. The population with 2n = 48 was genetically less variable than and distinct from the other populations. Population genetics in relation to cytogenetic data provided new insights regarding the genetic diversification and mating system of S. micranthum

Genetic Diversity and Chemical Profile of Rhodophiala bifida Populations from Brazil

Rhodophiala bifida (Herb.) Traub, Amaryllidaceae, is a species native to South America known to produce alkaloids with potential pharmacological uses such as montanine, which has anti-inflammatory potential. R. bifida could be applied as a natural source of montanine. It is important to understand the genetic diversity of this species in order to assess the sustainable use of this plant. The aim of this study was to evaluate the genetic diversity and chemical profiles of the two known natural populations of R. bifida in Brazil. This report is the first population genetic study of R. bifida. We studied 93 individuals with six Inter-Simple Sequence Repeats (ISSR) primers. A total of 79 loci were amplified. Our results showed high-population structure (Fst = 0.16), with greatest genetic variation at the intrapopulation level. Genetic analyses separated the individuals of R. bifida into two clusters that corresponded to each of the natural populations. Chemical profile evaluation was carried out on dried bulbs, leaves, flowers, and flower scapes by liquid chromatography and mass spectrometry. Montanine and nangustine were the main metabolites identified in both populations. These alkaloids concentrations differed by population and by plant part

Molecular Genetic Variability, Population Structure and Mating System in Tropical Forages

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyse population structure and genetic diversity, evolution and origin of the genetic variability in the centre of origin, mating systems and genetic resources in EMBRAPA’s germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work

A preliminary approach to the phylogeny of the genus Paspalum (Poaceae)

The present work intends to clarify the phylogenetic relationships among the species of Paspalum L. belonging to the informal groups Notata/Linearia and Dilatata, and to raise some preliminary hypotheses on the phylogeny of the genus as a whole. A combined dataset including morphological and molecular characters was used to analyze 28 species of Paspalum plus some representatives of related genera of the tribe Paniceae. Analyses were performed using both parsimony and maximum likelihood. The monophyly of Paspalum is not supported nor contradicted. The circumscription of informal groups of Paspalum is discussed, as well as the cladistic treatment of allopolyploid taxa, especially those comprising the Dilatata group. The relationships of members of the Dilatata with their putative progenitors is confirmed, but the monophyly of the group as a whole is not. A close relationship between P. dilatatum Poir. and P. lividum Trin. ex Schltdl. is shown. Our analysis is consistent with the monophyly of a group comprising Notata+Linearia, with a monophyletic Notata group nested within it. The delimitation of the core Notata is proposed by including P. conduplicatum Canto-Dorow, Valls and Longhi-Wagner, P. notatum Flüggé, P. minus E. Fourn., P. pumilum Nees and P. subciliatum Chase.Fil: Souza Chies, Tatiana T.. Universidade Federal do Rio Grande do Sul; BrasilFil: Essi, Liliana. Universidade Federal do Rio Grande do Sul; BrasilFil: Rua, Gabriel Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Botánica Agrícola; ArgentinaFil: Valls, José Francisco M.. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; BrasilFil: Miz, Rogéria B.. Universidade Federal do Rio Grande do Sul; Brasi

Phylogenetic analysis of Saccharum (Poaceae; Andropogoneae) with emphasis of the circumscription of the South American species

Premise of the study: Polyploidy and reticulate evolution are often a complication for discovering phylogenetic relationshipsbetween genera and species. Despite the huge economic importance of sugarcane ( Saccharum offi cinarum-Poaceae, Andropogoneae),the limits of the genus Saccharum and its species are complex and largely unresolved, involving both polyploidyand reticulate evolution. This study aimed to assess the phylogenetic relationships of Saccharum s.l. , including Erianthus andTripidium , as well as investigate the taxonomic circumscription of the South American species of the genus. Methods: Molecular cloning and sequencing of fi ve regions of four low-copy nuclear loci were performed, including Aberrantpanicle organization 1 ( apo 1), Dwarf 8 ( d 8), two exons of Erect panicle 2 ( ep 2 -ex 7 and ep 2 -ex 8), and Retarded palea 1 ( rep 1).Concatenated trees were reconstructed using Maximum Parsimony, Maximum Likelihood, and Bayesian Inference analyses. Key results: The allopolyploid origin of Saccharum was demonstrated using evidence from nuclear genes. The samples of Saccharums.l. grouped in two distinct clades, with S. arundinaceum and S. ravennae (= Tripidium, or Erianthus sect. Ripidium )apart from all other species analyzed of the genus. Saccharum angustifolium, S. asperum, and S. villosum correspond to distinctclades (different species). The plants with intermediate morphology between S. angustifolium and S. villosum presented a patternof paralogues consistent with a hybrid origin. Conclusions: Saccharum s.l. is polyphyletic and Tripidium should be recognized as a distinct genus. However, no strong evidencewas found to support the segregation of Erianthus. The taxonomic circumscription of the South American species of thegenus was resolved and the occurrence of natural hybrids was documented. Better understanding of the phylogenetic relationshipsof Saccharum and relatives may be useful for sugarcane breeders to identify potential taxa for interspecifi c and intergenericcrosses in the genetic improvement of sugarcane.Fil: Welker, Cassiano A. Dorneles. Pontificia Universidade Catolica Do Rio Grande Do Sul; BrasilFil: Souza-Chies, Tatiana T.. Universidade Federal Do Rio Grande Do Sul; BrasilFil: Longhi-Wagner, Hilda M.. Universidade Federal Do Rio Grande Do Sul; BrasilFil: Peichoto, Myriam Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: McKain, Michael R.. Donald Danforth Plant Science Center; Estados UnidosFil: Kellogg, Elizabeth Anne. Donald Danforth Plant Science Center; Estados Unido

Evolution of oil-producing trichomes in Sisyrinchium (Iridaceae): insights from the first comprehensive phylogenetic analysis of the genus.

International audienceBACKGROUND AND AIMS: Sisyrinchium (Iridaceae: Iridoideae: Sisyrinchieae) is one of the largest, most widespread and most taxonomically complex genera in Iridaceae, with all species except one native to the American continent. Phylogenetic relationships within the genus were investigated and the evolution of oil-producing structures related to specialized oil-bee pollination examined. METHODS: Phylogenetic analyses based on eight molecular markers obtained from 101 Sisyrinchium accessions representing 85 species were conducted in the first extensive phylogenetic analysis of the genus. Total evidence analyses confirmed the monophyly of the genus and retrieved nine major clades weakly connected to the subdivisions previously recognized. The resulting phylogenetic hypothesis was used to reconstruct biogeographical patterns, and to trace the evolutionary origin of glandular trichomes present in the flowers of several species. KEY RESULTS AND CONCLUSIONS: Glandular trichomes evolved three times independently in the genus. In two cases, these glandular trichomes are oil-secreting, suggesting that the corresponding flowers might be pollinated by oil-bees. Biogeographical patterns indicate expansions from Central America and the northern Andes to the subandean ranges between Chile and Argentina and to the extended area of the Paraná river basin. The distribution of oil-flower species across the phylogenetic trees suggests that oil-producing trichomes may have played a key role in the diversification of the genus, a hypothesis that requires future testing

A New Allopolyploid Species of Saccharum (Poaceae ‐ Andropogoneae) from South America, with Notes on its Cytogenetics

Allopolyploidy is a major mode of speciation in flowering plants and particularly in the grass tribe Andropogoneae, which includessugarcane (Saccharum officinarum) and relatives. A new species of Saccharum from South America (S. intermedium) is described here, supported bymorphological, molecular and cytogenetic evidence. Previous molecular analyses indicated an allopolyploid origin of the new species throughinterspecific hybridization between S. angustifolium and S. villosum. The new taxon has intermediate morphology between the two parental species.Cytogenetic analyses of the three species were performed, including chromosome counts, meiotic regularity, and pollen viability and morphology.The new taxon is hexaploid (2n = 60), while the parental species are triploids (2n = 30), confirming the ploidy level suggested by the number ofparalogues in phylogenetic trees based on low-copy nuclear genes. This represents the first chromosome count for S. intermedium and a new cytotypefor S. villosum. Although both parental species are triploids, they surprisingly exhibited regular meiosis and high pollen viability, indicating they aremale-fertile, as is the hexaploid new species. Data on geographic distribution and phenology is also presented, aswell as a key for the South Americanspecies of Saccharum.Fil: Welker, Cassiano A. D.. Universidade Federal de Uberlandia; BrasilFil: Souza Chies, Tatiana T.. Universidade Federal do Rio Grande do Sul; BrasilFil: Peichoto, Myriam Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Oliveira, Reyjane P.. Universidade Estadual de Feira de Santana; BrasilFil: Carvalho, Luana C.. Universidade Federal do Rio Grande do Sul; BrasilFil: Muccillo, Victória B. S.. Universidade Federal do Rio Grande do Sul; BrasilFil: Kellogg, Elizabeth Anne. Donald Danforth Plant Science Center; Estados UnidosFil: Kaltchuk-Santos, Eliane. Universidade Federal do Rio Grande do Sul; Brasi