Assessment of genetic diversity of Tunisian Barbary fig (Opuntia ficus indica) cultivars by RAPD markers and morphological traits

Abstract

In this work, we report the analysis of genetic diversity of Tunisian Opuntia ficus indica ecotypes using morphological parameters and RAPD markers. Morphological evaluation showed phenotypic variation among the accessions studied. The used phenotypic traits appear a good descriptors for Barbary fig varieties. The subsequent RAPD banding patterns exhibited large number of polymorphic bands. Ten primers were screened to assess their ability to detect polymorphisms within 28 Tunisian Barbary fig cultivars and revealed 41 polymorphic RAPD markers. The percentage of polymorphic bands (73.21%) and the resolving power (Rp) (24.17) showed the efficiency of the used primers. The revealed RAPD markers permit to distinguish all considered cultivars and resolve homonymy problem. UPGMA dendrogram and principal component analysis were performed to access patterns of diversity among cultivars and its structuration. In fact the cultivars distribution occurs independently of their geographic origin. The overall distribution pattern of molecular variation suggested that about 92.58% of the total variance was accounted within group. The remaining 7.42% of the variation was hierarchically structured between components due to differentiation among groups. A positive and significant correlation was evidenced between morphological descriptors and RAPD markers. Wide phenotypic and molecular diversity was found in local cactus germplasm indicating a considerable potential for improving this crop. The combined analysis of phenotypic and molecular markers was also a valuable tool for assessing the genetic diversity in cacti.