Patricia M Guimarães

Publications (2)6.03 Total impact

• Article: Matita, a new retroelement from peanut: characterization and evolutionary context in the light of the Arachis A-B genome divergence.

  Stephan Nielen, Bruna S Vidigal, Soraya C M Leal-Bertioli, Milind Ratnaparkhe, Andrew H Paterson, Olivier Garsmeur, Angélique D'Hont, Patricia M Guimarães, David J Bertioli
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  ABSTRACT: Cultivated peanut is an allotetraploid with an AB-genome. In order to learn more of the genomic structure of peanut, we characterized and studied the evolution of a retrotransposon originally isolated from a resistance gene analog (RGA)-containing bacterial artificial chromosome (BAC) clone. It is a moderate copy number Ty1-copia retrotransposon from the Bianca lineage and we named it Matita. Fluorescent in situ hybridization (FISH) experiments showed that Matita is mainly located on the distal regions of chromosome arms and is of approximately equal frequency on both A- and B-chromosomes. Its chromosome-specific hybridization pattern facilitates the identification of individual chromosomes, a useful cytogenetic tool considering that chromosomes in peanut are mostly metacentric and of similar size. Phylogenetic analysis of Matita elements, molecular dating of transposition events, and an estimation of the evolutionary divergence of the most probable A- and B-donor species suggest that Matita underwent its last major burst of transposition activity at around the same time of the A- and B-genome divergence about 3.5 million years ago. By probing BAC libraries with overgos probes for Matita, resistance gene analogues, and single- or low-copy genes, it was demonstrated that Matita is not randomly distributed in the genome but exhibits a significant tendency of being more abundant near resistance gene homologues than near single-copy genes. The described work is a further step towards broadening the knowledge on genomic and chromosomal structure of peanut and on its evolution.
  MGG Molecular & General Genetics 11/2011; 287(1):21-38. · 2.58 Impact Factor
• Source

  Available from: PubMed Central

  Article: BAC libraries construction from the ancestral diploid genomes of the allotetraploid cultivated peanut.

  Patricia M Guimarães, Olivier Garsmeur, Karina Proite, Soraya C M Leal-Bertioli, Guilhermo Seijo, Christian Chaine, David J Bertioli, Angelique D'Hont
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  ABSTRACT: Cultivated peanut, Arachis hypogaea is an allotetraploid of recent origin, with an AABB genome. In common with many other polyploids, it seems that a severe genetic bottle-neck was imposed at the species origin, via hybridisation of two wild species and spontaneous chromosome duplication. Therefore, the study of the genome of peanut is hampered both by the crop's low genetic diversity and its polyploidy. In contrast to cultivated peanut, most wild Arachis species are diploid with high genetic diversity. The study of diploid Arachis genomes is therefore attractive, both to simplify the construction of genetic and physical maps, and for the isolation and characterization of wild alleles. The most probable wild ancestors of cultivated peanut are A. duranensis and A. ipaënsis with genome types AA and BB respectively. We constructed and characterized two large-insert libraries in Bacterial Artificial Chromosome (BAC) vector, one for each of the diploid ancestral species. The libraries (AA and BB) are respectively c. 7.4 and c. 5.3 genome equivalents with low organelle contamination and average insert sizes of 110 and 100 kb. Both libraries were used for the isolation of clones containing genetically mapped legume anchor markers (single copy genes), and resistance gene analogues. These diploid BAC libraries are important tools for the isolation of wild alleles conferring resistances to biotic stresses, comparisons of orthologous regions of the AA and BB genomes with each other and with other legume species, and will facilitate the construction of a physical map.
  BMC Plant Biology 02/2008; 8:14. · 3.45 Impact Factor