Cytogenetic characterization of Tacinga Britton & Rose (Opuntioideae-Cactaceae)

• DOI: 10.22533/at.ed.9161915036

• Palavras-chave: Atena

• Keywords: Chromosome banding, autopoliploidy, transposable elements and Opuntioideae.

• Abstract:

  The Tacinga genus includes eight

  species; seven are endemic to eastern Brazil and

  only occur in Northeastern of Venezuela. They are

  shrubs, sub-shrubs and lianas, with segmented

  or cylindrical cladodes and abundant glochids

  in their areoles. Their morphological characters

  have limited utility to distinguish species and

  to infer about the genetic relationships among

  them. The present work aimed to characterize

  six Tacinga species at chromosome level using

  CMA/DAPI fluorochromes. Their chromosome

  numbers ranged from 2n = 22 (T. braunii,

  T. funalis and T. palmadora) to 2n = 66 (T.

  werneri), with relatively symmetrical karyotypes,

  predominantly metacentric chromosomes, and

  average chromosome size of 2.68 μm. The

  heterochromatic band pattern was characterized

  by the presence of at least one chromosome pair

  with conspicuous CMA+ terminal bands, usually

  linked and distended, with heteromorphims on

  CMA+ interstitial bands observed in T. funalis

  and T. inamoena. The autopoliploidy and action

  of the transposable elements are mechanisms

  that could explain chromosomal evolution in

  Tacinga. On the other hand, the morphological

  diversity among disjunct populations of T.

  inamoena should be a result of its interspecific

  crosses. Considering this assumption, T.

  inamoena seems to be an excellent material to

  study polyploid complexes in which tetraploid

  species are often hybrids.

• Número de páginas: 15