Study of genetic variation of wild threatened Cirrhinus reba (Hamilton 1822) through RAPD fingerprinting technique

Abstract

Cirrhinus reba, one of the very popular minor carp species is distributed in the Indian subcontinent including Bangladesh. The distribution of this species has greatly reduced and has become endemic in selected areas of Bangladesh. To conserve the species as well as for the inclusion of aquaculture, attempts were taken by several researcher for its fingerling production through induced breeding. To produce quality fish fingerling the genetic diversity needs to be considered, the present study was aimed to assess the genetic variation of wild C. reba collected from different regions of Bangladesh. Wild stocks of C. reba were collected from the rivers of Dinajpur, Bogura, Jashore and Mymensingh regions. The muscle tissue samples of 10 individuals from each region were collected and preserved for DNA extraction. A total of 10 RAPD primers with GC content ranged from 60-70% were screened for single individuals of each population. Out of ten primers screened, seven primers that gave amplified products were screened again to check the reproducibility and stability of the bands. Finally, seven primers which produced clear, reproducible, and produced both monomorphic and polymorphic bands were selected to reveal the genetic variation of four wild populations of C. reba. The data were analyzed using MS Excel, GenAlex, and PAST. The highest numbers of bands (12) in all the C. reba populations were observed with primer OP E-15 and lowest (7) with primer OP E-05. The fragment size detected with these seven primers ranged from 300-1000bp. The highest (80%) and lowest (45%) percentage of polymorphic bands across the primers were observed in the Jashore and the Bogura population. The highest pair-wise genetic variation were detected in between Bogura and Dinajpur Population (0.223) and lowest in between Jashore and Dinajpur Population (0.126). The highest gene flow (Nm=1.516) was found between the Bogura and the Jashore populations, whereas the lowest value (Nm=0.467) was observed between the Bogura and the Dinajpur populations. The UPGMA dendrogram based on genetic distance indicated that the segregation of four population of C. reba into two clusters: the Bogura population formed cluster I and three other population formed cluster II. The second cluster was further sub-divided into two subgroups: the Mymensingh and Dinajpur population formed sister group where Jashore was separated.