Heterosis analysis in strain-crossed hybrid Rohu (Labeo Rohita) through mMicrosatellite DNA variability assay

Labeo rohita is an important commercial aquaculture species in Bangladesh, but it needs improved growth performance to meet the increasing demand for fish. Genetic improvement through inter-strain crossing, generating heterosis, is quicker than a selection strategy. Therefore, crosses were made between two strains of rohu: Padma River strain and a hatchery strain. Growth performance analyis showed the highest growth rate in the Padma × Padma cross followed by one of the reciprocal crosses Hatchery♂ × Padma♀ (hybrid). The lowest growth rate was observed in Hatchery × Hatchery cross. DNA variability study using three microsatellite markers showed polymorphism (P95) in these crosses. Variations were observed in number and frequencies of alleles and mean heterozygosity in different loci; the mean number of alleles varied from 4.667±0.882, 3.333±1.333 and 2.667±1.202 in Padma, hybrid and Hatchery strains respectively. Relatively high levels of gene flow and low Strain differentiation (FST) values were found between the Padma and hybrid strains. The UPGMA dendrogram based on genetic distance placed the Padma population in one cluster and the hybrid and Hatchery populations in another. The results revealed that there was relatively low level of genetic variability in the riverine and hatchery reared populations of L. rohita in Bangladesh