Morphological characterization and phylogenetic distance among several genotypes of Rebutia, Aylostera, Mediolobivia and Sulcorebutia (Cactaceae)

Abstract

Four genera and 75 species belonging to Cactaceae family were investigated regarding their morphology and their molecular polymorphism. The botanical classification that described the phenotypic aspects of different characters, such as number of spines/areoles, length of spines and flower diameter, was used to describe the main peculiarities (morphological method). In Rebutia genus, the floral diameter varied between small limits: 2 cm (R. xanthocarpa v. splendens, and R. brachyantha) to 4.5 cm in R. calliantha and R. marsoneri (the greatest floral diameter from all the studied species). Of the studied species of Aylostera genus, A. fiebrigii has the greatest length of the spines and A. narvaecensis the smallest one. The analysis of the plants morphology showed a relatively low variability of biological material, according to genus and species. The genetic diversity was calculated with Nei and Li’s index, and the phylogenetic tree (dendrogram) was generated with a neighbor-joining program. The dendrogram indicates the diversity of the genotypes, which are grouped into three distinctive large groups. The largest group includes species from the Mediolobivia and Rebutia genera, which clearly share a common ancestor; the group shares a common ancestor with B  and C as well; A includes some but all not descendents. Species from Rebutia genus were present in all the described groups. The genetic distance between species from Rebutia, Mediolobivia, Aylostera and Sulcorebutia genera is small and the differences between the main characters was also quite small, so the trend of combining these species in one genus is justified.

Key words: Cactaceae family, DNA isolation, dendrogram, phenotypic traits, genetic distance.