Cytogenetics of tuna in Argentina (two forms of Opuntia ficus-indica (L.) Mill. and O. robusta J. C. Wendl., Cactaceae)

AHUMADA LUJÁN; MONTENEGRO GONZALO; TRILLO CECILIA; UÑATES DIEGO; BERNARDELLO GABRIEL; LAS PEÑAS LAURA

Geneti Resour Crop Evol

Springer

Año: 2019

1573-5109

Opuntia ficus-indica (L.) Mill. f. ficusindica(yellow tuna, cordobesa orange tuna, italianaorange tuna, salten?a tuna) and f. amyclaea (white tuna,reddish tuna) and O. robusta J. C. Wendl. (cuaresmatuna) are extensively cultivated cacti in Argentina,mainly used as fodder and human food. Despite theimportance of these resources, no studies of molecularcytogenetics considering the morphological characteristicsof the varieties have been carried out. Themain goal of this contribution is to determine thechromosome number, physical localization of ribosomalgenes and amount of DNA in these taxa, includingseveral populations with different fruit colors. The f.ficus-indica samples were octoploid, f. amyclaeahexaploid, and O. rubusta tetraploid. All taxa exhibitedsmall similar-sized symmetrical chromosomes.Karyotypes were symmetrical with slight variationswithin each species. The 18S?5.8S?26S sites in alltaxa were located on the secondary constrictions andthe adjacent satellites at telomeric positions. The f.ficus-indica presented four 18S?5.8S?26S rDNA sitesand the f. amyclaea three, whereas O. robusta had two.There were eight and six 5S rDNA sites in f. ficusindicaand f. amyclaea, respectively, and four in O.robusta. They were always proximally located onshort arms of different chromosome pairs, always in apericentromeric position. Both ribosomal genes werealways asynthenic. The nuclear DNA in the octoploidf. ficus-indica presented a lower value (1Cx = 0.91pg) than the hexaploid f.amyclaea (1Cx = 1.06 pg),whereas the tetraploid O. robusta had 1Cx = 0.87 pg.This cytogenetic evaluation is important for developingmore efficient and faster selection strategies,contributing to obtaining new and improved varieties.