Search

Fil: Talavera Stefani, Liliana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología Subtropical. Nodo Posadas; Argentina. Fil: Talavera Stéfani, Liliana Noelia. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina. Fil: Argüelles, Carina Francisca. Universidad Nacional de Misiones. Instituto de Biología Subtropical. Nodo Posadas; Argentina Fil: Seijo, José Guillermo. Consejo Nacional Investigaciones Científicas y Técnicas. Instituto de Botánica del Nordeste; Argentina. La “yerba mate”, Ilex paraguariensis A. St.-Hil (Aquifoliaceae) es una especie arbórea de gran importancia económica y cultural para Sudamérica. Actualmente sólo persisten escasas poblaciones naturales en remanentes de su área de distribución original. Existen, además poblaciones cultivadas antiguas en las regiones productivas instaladas previas al inicio del proceso de domesticación y mejoramiento genético de la especie. Con el fin de contribuir al diseño de estrategias de conservación y manejo racional de los recursos fitogenéticos de esta especie, el objetivo de esta tesis fue estimar la variabilidad genética e inferir el patrón de distribución I. paraguariensis, en poblaciones naturales y en cultivos antiguos de de Argentina, Paraguay y Uruguay. Se incluyeron en el análisis un total de 26 puntos de muestreo ubicados en los tres países, los que incluyeron 9 poblaciones naturales, 14 cultivos antiguos e individuos aislados de diversas procedencias. Para los análisis genéticos se utilizaron regiones cloroplásticas, así como diversas secuencias y marcadores nucleares. Las regiones cloroplásticas fueron monomórficas en todas las poblaciones analizadas, mientras que los marcadores nucleares resultaron altamente polimórficos e informativos. En la región ITS1-ITS2 del ADNr 45S se identificaron 18 sitios polimórficos, distribuidos en 25 ribotipos, muchos de los cuales fueron exclusivos tanto para poblaciones naturales como para cultivadas. Para el caso de marcadores SSRs/STRs se identificaron un total de 12, 13 y 18 alelos para los loci Ipg_10, Ipg_03 e Ipg_01 respectivamente, de estos, 16 fueron exclusivos para ciertas poblaciones naturales y cultivadas. La He promedio fue variable en un rango de 0,218 a 0,753. Del total de la variación observada por medio de estos marcadores sólo el 11% correspondió a diferencias entre las poblaciones. El AMOVA mostró, además, una moderada diferenciación genética entre las mismas. Las muestras fueron agrupadas en dos clústeres: uno de ellos correspondió a la única población natural de Uruguay estudiada mientras que el segundo agrupó al resto de las poblaciones tanto cultivadas como naturales de Paraguay y Argentina. Mediante la tecnología DArTseq fueron identificados 9.793 marcadores SNPs, que mostraron un promedio de He en cada individuo de 0,055 a 0,236. Los individuos de la población uruguaya presentaron los valores más bajos mientras que valores más altos se observaron en individuos de dos poblaciones naturales y dos cultivadas antiguas de Argentina. El coeficiente de rareza (R), estuvo entre 0,649 y 3,027, evidenciando que cada población constituye un importante reservorio de alelos particulares. Los análisis realizados mediante escalamiento multidimensional y la agrupación mediante el método de Ward no mostraron claras diferencias entre las poblaciones argentinas y paraguayas incluidas en el análisis, aunque sí una marcada distancia genética con respecto a la población uruguaya. Las poblaciones naturales de Argentina, y algunas cultivadas del noreste de Misiones, son las que presentan menor distancia genética respecto de la población uruguaya. Asimismo, todas las poblaciones cultivadas tendieron a agruparse entre sí, aunque se solaparon con algunas poblaciones naturales. Los resultados evidenciaron que tanto las poblaciones cultivadas antiguas como los remanentes naturales constituyen importantes reservorios de variabilidad genética, particularmente por la presencia de alelos exclusivos para los marcadores SNPs en todas las poblaciones, los que corresponderían principalmente a regiones codificantes. Estos resultados evidencian la necesidad de diseñar planes de conservación complementarios que incluyan conservación in situ de poblaciones naturales y cultivadas, así como el rescate de genotipos para su preservación ex situ. Yerba mate, Ilex paraguariensis A. St.-Hil (Aquifoliaceae) is a tree species of great economic and cultural importance for South América. At present, only few natural populations persist in remnants of its original area of distribution. There are also ancient cultivated populations in the productive regions implanted before the beginning of the domestication process and genetic improvement of the species. With the purpose of contributing to the design of conservation strategies and rational management of this phytogenetic resource, the objective of this work was to estimate the genetic variability of I. paraguariensis and to infer the distribution pattern in nature and in ancient cultivated populations from Argentina, Paraguay, and Uruguay. A total of 26 sampling points located in Argentina, Paraguay and Uruguay were incorporated in the analysis, which included 9 natural populations, 14 ancient cultivated populations, as well as individuals isolated from diverse origins. Chloroplastic regions as well as various nuclear sequences and nuclear markers were used for genetic analysis. Chloroplastic regions were monomorphic in all tested populations, while nuclear markers were polymorphic and informative. In the ITS1-ITS2 region of rDNA 45S, 18 polymorphic sites were identified, distributed in 25 ribotypes, many of which were exclusive for both natural and cultivated populations. In the case of SSRs/STRs markers, a total of 12, 13 and 18 alleles were identified for Ipg_10, Ipg_03 and Ipg_01 loci, respectively, of which 16 were exclusive to certain nature and ancient cultivated populations. The average He varied in a range from 0.218 to 0.753. Of the total variation observed through these markers, only 11% corresponded to differences among populations. The AMOVA also showed a moderate genetic differentiation between them. The samples were grouped into two clusters: one of them corresponded to the only natural population of Uruguay studied while the second one grouped the rest of the cultivated and natural populations of Paraguay and Argentina. Using DArTseq technology, 9,793 SNPs markers were identified, showing an average He per individual that range from 0.055 to 0.236. The individuals of the Uruguay population presented the lowest values, while higher values were observed in individuals of two natural populations and two ancient cultivated populations from Argentina. The rarity coefficient (R) was between 0.649 and 3.027, evidencing that each population is an important reservoir of private alleles. The analyses carried out by means of multidimensional scaling and grouping analyses carried using the Ward's method did not show clear differences between the Argentinean and Paraguayan populations, although a marked genetic distance with respect to the Uruguayan population did. The natural populations of Argentina, and some cultivated in the northeast of Misiones are the ones that present the least genetic distance with respect to the Uruguayan population. All cultivated populations tend to group together, although they overlap with some natural populations. The results showed that both ancient cultivated populations and natural remnants are important reservoirs of genetic variability, particularly because the presence of exclusive alleles of SNPs makers in all populations, which would correspond mainly to coding sequences. These results demonstrate the need to design complementary conservation strategies, including in-situ conservation of natural and cultivated populations as well as the rescue of genotypes for ex-situ preservation.

In recent years the growing interest in the conservation of Paraná River’s riparian forest led to the discovery of botanical novelties for Argentina. Populations of Calophyllum brasiliense Camb. (Calophyllaceae), a typically flooded lowlands species, were identified in the remaining hygrophile forest of northeast Argentina and southeast Paraguay. Deforestation and flooding, due to the construction of dams, have caused these populations to suffer intensive fragmentation. The aim of this work was to infer phylogeographic relationships among five populations of C. brasiliense, three from Argentina and two from Paraguay, which represent the southernmost points of species’ distribution. We also compared them with samples of a C. brasiliense population from Mexico, the northernmost edge of the species distribution. The chloroplast intergenic spacers petG-trnP, psbJ-petA and the trnL-UAA chloroplast intron were amplified from leaves’ DNA. A total of 2234 bp were characterized once the three regions were analyzed. The three chloroplast regions showed nucleotide differences, represented by InDels, inversions and a few SNPs; however, only the trnL intron was selected for further phylogeographic analysis due to the amount of the information obtained for all populations. Based on trnL intron, it was possible to estimate nucleotide and haplotype diversity (π = 0.00237 and Hd = 0.29600, respectively). Three haplotypes were identified, which allowed Argentinean, Paraguayan and Mexican populations to be differentiated. Based on the three haplotypes found, we discuss and propose a model for a C. brasiliense’ geographic dispersion and historical colonization routes, including an alternative new one to the well-known of the Paraná River., Facultad de Ciencias Naturales y Museo, Laboratorio de Sistemática y Biología Evolutiva