A microsatellite-based linkage map of salt tolerant tilapia (Oreochromis mossambicus x Oreochromis spp.) and mapping of sex-determining loci

Abstract

BackgroundTilapia is the common name for a group of cichlid fishes and is one of the most important aquacultured freshwater food fish. Mozambique tilapia and its hybrids, including red tilapia are main representatives of salt tolerant tilapias. A linkage map is an essential framework for mapping QTL for important traits, positional cloning of genes and understanding of genome evolution.ResultsWe constructed a consensus linkage map of Mozambique tilapia and red tilapia using 95 individuals from two F1 families and 401 microsatellites including 282 EST-derived markers. In addition, we conducted comparative mapping and searched for sex-determining loci on the whole genome. These 401 microsatellites were assigned to 22 linkage groups. The map spanned 1067.6 cM with an average inter-marker distance of 3.3 cM. Comparative mapping between tilapia and stickleback, medaka, pufferfish and zebrafish revealed clear homologous relationships between chromosomes from different species. We found evidence for the fusion of two sets of two independent chromosomes forming two new chromosome pairs, leading to a reduction of 24 chromosome pairs in their ancestor to 22 pairs in tilapias. The XY sex determination locus in Mozambique tilapia was mapped on LG1, and verified in five families containing 549 individuals. The major XY sex determination locus in red tilapia was located on LG22, and verified in two families containing 275 individuals.ConclusionsA first-generation linkage map of salt tolerant tilapia was constructed using 401 microsatellites. Two separate fusions of two sets of two independent chromosomes may lead to a reduction of 24 chromosome pairs in their ancestor to 22 pairs in tilapias. The XY sex-determining loci from Mozambique tilapia and red tilapia were mapped on LG1 and LG22, respectively. This map provides a useful resource for QTL mapping for important traits and comparative genome studies. The DNA markers linked to the sex-determining loci could be used in the selection of YY males for breeding all-male populations of salt tolerant tilapia, as well as in studies on mechanisms of sex determination in fish.

Preliminary genetic linkage map of Indian major carp, Labeo rohita (Hamilton 1822) based on microsatellite markers

“…The percentage of markers placed in LGs with significant linkage (LOD ≥ 3.0) in the present investigation is comparatively less than that reported in other aquatic species (Sekino and Hara 2007;Shen et al 2007;Bouza et al 2007;Li et al 2012;Liu et al 2013). This may be due to several factors like marker polymorphism, distribution of markers in the genome, crossover distribution in the genome, mapping population size and type, and mapping strategy (Liu 1998).…”

“…Genetic linkage map for a number of aquatic species have been constructed (Moen et al 2008;Jiang et al 2013;Liu et al 2013;Dor et al 2014;Hermida et al 2014;Keong et al 2014;Hollenbeck et al 2015) using different types of polymorphic markers. Owing to their abundance in the * For correspondence.…”

The Tilapias' Chromosomes Influencing Sex Determination

“…3 ), are in contradiction with cytological analyses showing delayed pairing in synaptonemal complex and differential distribution of repetitive DNAs at the tilapia largest chromosome (corresponding to LG3) [Carrasco et al, 1999;Ferreira and Martins, 2008;Campos-Ramos et al, 2009]. A recent study with O. mossambicus and a hybrid red tilapia strain placed the O. mossambicus sex-determination locus on LG1 and that of the hybrid strain on LG23 [Liu et al, 2013].…”

A Comprehensive Transcriptome Provides Candidate Genes for Sex Determination/Differentiation and SSR/SNP Markers in Yellow Catfish

“…Sex dimorphic growth pattern has been found in many species of teleost fish (Gui 2007;Mei and Gui 2014), and the significant growth difference between female and male and its application implications have been noted in some farmed fish (Taranger et al 2010;Gui and Zhou 2010;Gui and Zhu 2012;Kobayashi et al 2013;Liu et al 2013a). Yellow catfish (Pelteobagrus fulvidraco), one of the important freshwater fish species in Asia, has been widely cultured for its delicious flesh and high nutritive value (Huang et al 1999).…”