Cytomelecular characterization of Opuntia spp. accessions from INSA germplsm bank

The knowledge of both genetic and cytogenetic traits in Opuntia are essential to define the best strategies to develop new cultivars. The objective of the present work was to characterize some Opuntia accessions from INSA germplasm bank, localized in Campina Grande, Paraiba state, Brazil. The accessions were chosen due to their forage potential and cochineal resistance. Some cytogenetic analyses were developed in 15 accessions from both O. atropes and O cochenilifera species, using CMA/DAPI and flow cytometry, in order to confirm their chromosome numbers, ploidy levels and DNA content. The same accessions were molecularly analyzed using eight ISSR primers. All materials were identified as diploids (2n = 2x = 22) and showed one chromosome pair with CMA+ terminal bands. Their DNA content varied between 1.45 pg, in accession 03 of O. atropes, and 4.27 pg in the accession 64 of O. cochenillifera. Some endopolyploid events were also observed. The ISSR markers from PCR were able to distinguish all accessions in intraspecific level and showed a significant genetic diversity is the germplasm bank, that is also essential to develop a cactus pear genetic breeding program.