Genetic diversity of Opuntia spp. varieties assessed by classical marker tools (RAPD and ISSR)

摘要

Opuntia, commonly named "nopal" in Mexico, is an important crop for its agronomical, economical, ecological and cultural value. Furthermore, it is known for its taxonomic complexity. In this paper, we report the genetic variability of 52 Opuntia cultivars with agronomic and economic importance, classified into 12 different species using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSR) markers. Ten primers, five for each marker type, were selected to assess their ability to detect polymorphisms in this plant accesions/varieties. Both marker systems generated a total of 307 bands, of which 50.8 % were polymorphic with an average of 15.6 polymorphic bands per primer. Thus, we assume that Mexican Opuntia varieties present broad genetic variation. Based on percentage of polymorphic bands; resolving power; polymorphic information content; and Marker Index, the K-12 (RAPD) and IS-06 (ISSR) primers were the most informative ones. Clusters obtained from RAPD, ISSR and a combination of both data sets did not match the actual taxonomic classification. On the other hand, the putative varieties currently classified in the same species were not located in the same cluster. Besides, the varieties included in O. ficus-indica, O. albicarpa and O. megacantha showed broad variation but were not well defined into separate clades; these cultivars possibly have common ancestry. The results presented here support our hypothesis about the existence of a smaller number of Opuntia species in accordance with those currently described, but with high intraspecific genetic variation.