Molecular characterization of Nile tilapia (Oreochromis niloticus L.) in Santa Catarina, Brazil

Fishery plays an important role in the supply of food for the increasing population. Tilapia production exceeded twomillion tons, being the second most important group of fish worldwide. Nile tilapia (Oreochromis niloticusLinnaeus, 1758) is the most important species due to the fast growth rates and good acceptance by the consumer.Fish genetic improvement is highly based on molecular genetics, including RAPD, and the knowledge obtained inthe last decades gave good results in terms of molecular marker-assisted breeding. In the present work the geneticvariability of four populations of Nile tilapia was assessed using molecular techniques. Modifications in the DNAextraction protocol described by Bardakci and Skibinski (1994) were evaluated, which was followed by theapplication of the RAPD technique, using eight primers and twenty specimens of four tilapia lineages (Bouaké,Chitralada, GST and GIFT). The results from the PCR amplifications were evaluated using the programs NTSysand PopGen. GIFT was the most polymorphic group, with 37% of its loci showing polymorphism, and the groupthat presented the highest Shannon index (0,17). All primers but one (OPA-12 for the lineage Chitralada) showedbands that can be used as a diagnostic tool for lineage differentiation. The dendrogram generated with thepolymorphic bands clearly separated the four populations; GIFT and Chitralada presented the highest geneticsimilarity (0,88), whereas GIFT and GST presented the highest genetic distance (0,23).