QTL Fine Mapping for Sex Determination Region in Bighead Carp (Hypophthalmichthys nobilis) and Comparison with Silver Carp (Hypophthalmichthys molitrix)
Bighead carp (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix) are genetically close aquaculture fish in the Cyprinidae, which have been confirmed to hold XX/XY sex determination. However, genomic locations of potential sex-related loci in these two fishes are still unknown. In this study, a high-resolution genetic linkage map was constructed by using 2976 SNP and 924 microsatellite markers in a F1 full-sib family of bighead carp, the length of which spanned 2022.34 cM with an average inter-marker distance of 0.52 cM. Comparative genomics revealed a high level of genomic synteny between bighead carp and zebrafish as well as grass carp. QTL fine mapping for sex trait was performed based on this linkage map of bighead carp and an unpublished linkage map of silver carp. A map distance of 3.863 cM (69.787–73.650 cM) on LG19 of bighead carp and 4.705 cM (79.096–83.801 cM) on LG21 of silver carp was significantly associated with sex phenotypes, and these two LGs are homologous between two fish species. Fourteen markers harboring in these regions were in strong linkage disequilibrium with the sex phenotype variance explained (PVE) varying from 89 to 100%. Two common markers were mapped on the QTL regions of bighead carp and silver carp, suggesting that these two carp species may have similar genetic bases for sex determination. Eleven potentially sex-related genes were identified within or near the sex QTL markers in two species. This study provided insights into elucidating mechanisms and evolution of sex determination in cyprinid fishes.
KeywordsQTL Sex determination region Comparative mapping Bighead carp Silver carp Sex-related genes
We would like to thank all colleagues of our lab (Meixia Pang, Xueli Liu, Baojiang Gan) for sample preparation and laboratory technical assistance.
JT conceived this study and guided the experiments. YZ and HL carried out the experiments and wrote the manuscript. BF performed bioinformatic analysis. XW and XY performed experiments and prepared mapping animals. All authors read and approved the final manuscript.
This research was supported by the National Key Research and Development Program (No. 2018YFD009102) and State Key Laboratory of Freshwater Ecology and Biotechnology (2019FBZ04).
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
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