A large number of single nucleotide polymorphisms (SNPs) have been identified in common carp (Cyprinus carpio) but, as yet, no high-throughput genotyping platform is available for this species. C. carpio is an important aquaculture species that accounts for nearly 14% of freshwater aquaculture production worldwide. We have developed an array for C. carpio with 250,000 SNPs and evaluated its performance using samples from various strains of C. carpio.

Amur ide (Leuciscus waleckii) is an economically and ecologically important cyprinid species in Northern Asia. The Dali Nor population living in the soda lake Dali Nor can adapt the extremely high alkalinity, providing us a valuable material to understand the adaptation mechanism against extreme environmental stress in teleost.

Common carp (Cyprinus carpio), a member of Cyprinidae, is the third most important aquaculture species in the world with an annual global production of 3.4 million metric tons, accounting for nearly 14% of the all freshwater aquaculture production in the world. Apparently genomic resources are needed for this species in order to study its performance and production traits. In spite of much progress, no physical maps have been available for common carp. The objective of this project was to generate a BAC-based physical map using fluorescent restriction fingerprinting. The first generation of common carp physical map was constructed using four- color High Information Content Fingerprinting (HICF). A total of 72,158 BAC clones were analyzed that generated 67,493 valid fingerprints (5.5 × genome coverage). These BAC clones were assembled into 3,696 contigs with the average length of 476 kb and a N50 length of 688 kb, representing approximately 1.76 Gb of the common carp genome. The largest contig contained 171 BAC clones with the physical length of 3.12 Mb. There are 761 contigs longer than the N50, and these contigs should be the most useful resource for future integrations with linkage map and whole genome sequence assembly. The common carp physical map is available at http://genomics.cafs.ac.cn/fpc/WebAGCoL/Carp/WebFPC/ . The reported common carp physical map is the first physical map of the common carp genome. It should be a valuable genome resource facilitating whole genome sequence assembly and characterization of position-based genes important for aquaculture traits.

In order to supply sufficient microsatellite loci for high-density linkage mapping, whole genome shotgun (WGS) sequences of the common carp (Cyprinus carpio) were assembled and surveyed for microsatellite identification. A total of 79,014 microsatellites were collected which were harbored in 68,827 distinct contig sequences. These microsatellites were characterized in the common carp genome. Information of all microsatellites, including previously published BAC-based microsatellites, was then stored in a MySQL database, and a web-based database interface (http://genomics.cafs.ac.cn/ssrdb) was built for public access and download. A total of 3,110 microsatellites, including 1,845 from WGS and 1,265 from BAC end sequences (BES), were tested and genotyped on a mapping family with 192 individuals. A total of 963 microsatellites markers were validated with polymorphism in the mapping family. They will soon be used for high-density linkage mapping with a vast number of polymorphic SNP markers.

As an essential environmental factor that affects the economic benefits of aquaculture, hypoxia is one of the urgent problems to be solved in the aquaculture fish breeding industry. Common carp (Cyprinus carpio) is a critical economic fish in China, and at present, there are many breeding strains of common carp with different character advantages in China, including Hebao red carp (C. carpio var wuyuanesis) and Songpu mirror carp (C. carpio var specularis). Even if the environmental adaptation of common carp is generally strong, the genetic background of hypoxia tolerance in different strains of common carp is unclear yet. This study tested the hypoxia tolerance of Songpu minor carp, Hebao red carp, and their hybrid F1 population by an acute hypoxia treatment. Muscle and liver tissues were used for transcriptome sequencing analysis to identify the key factors for hypoxia tolerance and explore the potential genetic mechanism for breeding high hypoxia tolerance in common carp. The comparative transcriptomic analysis revealed abundant hypoxia response-related genes and their differential regulation mechanism in these two tissues of different common carp strains under acute hypoxia, including immune response, cellular stress response, HIFs (hypoxia-inducible factors), MAP kinase, iron ion binding, and heme binding. Our findings will facilitate future investigation on the hypoxia response mechanism and provide a solid theoretical basis for breeding projects in common carp.

Various salmonid species are cultivated in cold water aquaculture. However, due to limited genomic data resources, specific high-throughput genotyping tools are not available to many of the salmonid species. In this study, a 57K single nucleotide polymorphism (SNP) array for rainbow trout (Oncorhynchus mykiss) was utilized to detect polymorphisms in seven salmonid species, including Hucho taimen, Oncorhynchus masou, Salvelinus fontinalis, Brachymystax lenok, Salvelinus leucomaenis, O. kisutch, and O. mykiss. The number of polymorphic markers per population ranged from 3,844 (O. kisutch) to 53,734 (O. mykiss), indicating that the rainbow trout SNP array was applicable as a universal genotyping tool for other salmonid species. Among the six other salmonid populations from four genera, 28,882 SNPs were shared, whereas 525 SNPs were polymorphic in all four genera. The genetic diversity and population relationships of the seven salmonid species were studied by principal component analysis (PCA). The phylogenetic relationships among populations were analyzed using the maximum likelihood method, which indicated that the shared SNP markers provide reliable genomic information for population genetic analyses in common aquaculture salmonid fishes. Furthermore, this obtained genomic information may be applicable for population genetic evaluation, marker-assisted breeding, and propagative parent selection in fry production.