Diego Hojsgaard

Publications (9) View all

• Source

  Available from: Eric Javier Martínez

  Dataset: Hojsgaard et al. 2013. New Phytologist 197, 336-347

  Diego H Hojsgaard, Eric J Martínez, Camilo L Quarin
• Source

  Available from: Eric Javier Martínez

  Article: Competition between meiotic and apomictic pathways during ovule and seed development results in clonality.

  Diego H Hojsgaard, Eric J Martínez, Camilo L Quarin
  [show abstract] [hide abstract]
  ABSTRACT: Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring. A high variation in the frequencies of sexual and apomictic pathways occurred at the first two stages. A trend of radical decline in realized sexuality was then observed. Sexual and apomictic seeds were produced, but the efficiency of the sexual pathway dropped drastically, and exclusively clonal offspring remained. Both reproductive pathways are unstable at the beginning of development, and only the apomictic one remains functional. Key factors reducing sexuality are the faster growth and parthenogenetic development in the aposporous pathway, and an (epi)genetically negative background related to the extensive gene de-regulation pattern responsible for apomixis. The effects of inbreeding depression during post-fertilization development may further decrease the frequency of effective sexuality.
  New Phytologist 11/2012; · 6.64 Impact Factor
• Source

  Available from: Eric Javier Martínez

  Article: A molecular map of the apomixis-control locus in Paspalum procurrens and its comparative analysis with other species of Paspalum

  D. H. Hojsgaard, E. J. Martínez, C. A. Acuña, C. L. Quarin, F. Pupilli
  [show abstract] [hide abstract]
  ABSTRACT: Since apomixis was first mapped in Paspalum, the absence of recombination that characterizes the related locus appeared to be the most difficult bottleneck to overcome for the dissection of the genetic determinants that control this trait. An approach to break the block of recombination was developed in this genus through an among-species comparative mapping strategy. A new apomictic species, P. procurrens (Q4094) was crossed with a sexual plant of P. simplex and their progeny was classified for reproductive mode with the aid of morphological, embryological and genetic analyses. On this progeny, a set of heterologous rice RFLP markers strictly co-segregating in coupling phase with apomixis was identified. These markers were all located on the telomeric region of the long arm of the chromosome 12 of rice. In spite of the lack of recombination exhibited by the apomixis-linked markers in P. procurrens, a comparative mapping analysis among P. simplex, P. malacophyllum, P. notatum and P. procurrens, allowed us to identify a small group of markers co-segregating with apomixis in all these species. These markers bracketed a chromosome region that likely contains all the genetic determinants of apomictic reproduction in Paspalum. The implications of this new inter-specific approach for overcoming the block of recombination to isolate the genetic determinants of apomixis and gain a better comprehension of genome structure of apomictic chromosome region are discussed.
  Theoretical and Applied Genetics 04/2012; 123(6):959-971. · 3.30 Impact Factor
• Source

  Available from: Mauro Grabiele

  Article: Chromosome studies in Orchidaceae from Argentina.

  Julio Rubén Daviña, Mauro Grabiele, Juan Carlos Cerutti, Diego Hernán Hojsgaard, Rubén Dario Almada, Irma Stella Insaurralde, Ana Isabel Honfi
  [show abstract] [hide abstract]
  ABSTRACT: The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here. Five chromosome records are the first ones at the genus level; these taxa are Aspidogyne kuckzinskii (2n = 42), Eurystyles actinosophila (2n = 56), Skeptrostachys paraguayensis (2n = 46), Stigmatosema polyaden (2n = 40) and Zygostates alleniana (2n = 54). In addition, a chromosome number is presented for the first time for 15 species: Corymborkis flava (2n = 56), Cyclopogon callophyllus (2n = 28), C. oliganthus (2n = 64), Cyrtopodium hatschbachii (2n = 46), C. palmifrons (2n = 46), Galeandra beyrichii (2n = 54), Habenaria bractescens (2n = 44), Oncidium edwallii (2n = 42), O. fimbriatum (2n = 56), O. pubes (2n = 84), O. riograndense (2n = 56), Pelexia ekmanii (2n = 46), P. lindmanii (2n = 46) and Warrea warreana (2n = 48). For Oncidium longicornu (2n = 42), O. divaricatum (2n = 56) and Sarcoglottis fasciculata (2n = 46+1B?, 46+3B?), a new cytotype was found. Chromosome data support phylogenetic relationships proposed by previous cytological, morphologic and molecular analyses, and in all the cases cover some gaps in the South American literature on orchid chromosomes.
  Genetics and Molecular Biology 10/2009; 32(4):811-21. · 0.63 Impact Factor
• Article: A molecular map of the apomixis-control locus in Paspalum procurrens and its comparative analysis with other species of Paspalum.

  D H Hojsgaard, E J Martínez, C A Acuña, C L Quarin, F Pupilli
  [show abstract] [hide abstract]
  ABSTRACT: Since apomixis was first mapped in Paspalum, the absence of recombination that characterizes the related locus appeared to be the most difficult bottleneck to overcome for the dissection of the genetic determinants that control this trait. An approach to break the block of recombination was developed in this genus through an among-species comparative mapping strategy. A new apomictic species, P. procurrens (Q4094) was crossed with a sexual plant of P. simplex and their progeny was classified for reproductive mode with the aid of morphological, embryological and genetic analyses. On this progeny, a set of heterologous rice RFLP markers strictly co-segregating in coupling phase with apomixis was identified. These markers were all located on the telomeric region of the long arm of the chromosome 12 of rice. In spite of the lack of recombination exhibited by the apomixis-linked markers in P. procurrens, a comparative mapping analysis among P. simplex, P. malacophyllum, P. notatum and P. procurrens, allowed us to identify a small group of markers co-segregating with apomixis in all these species. These markers bracketed a chromosome region that likely contains all the genetic determinants of apomictic reproduction in Paspalum. The implications of this new inter-specific approach for overcoming the block of recombination to isolate the genetic determinants of apomixis and gain a better comprehension of genome structure of apomictic chromosome region are discussed.
  Theoretical and Applied Genetics 06/2011; 123(6):959-71. · 3.30 Impact Factor