Abstract
The largemouth bass is an important species, and its culture has risen sharply with the surge in fish aquaculture in China. Due to the lack of selective breeding technology for the largemouth bass, the growth rate and disease resistance are low, its sexual maturation is slow, and other serious problems are contributing to a sharp decline in the safety and quality of largemouth bass products in recent decades. Therefore, comprehensive breeding programs to improve the economic performance and promote the modern industrial development of largemouth bass must be considered a priority. Here, a total of 152 adult largemouth bass, including two parents and 150 progenies, were selected to produce the genetic mapping family. Then, a high-density linkage map was constructed based on restriction site–associated DNA sequencing using 6,917 single-nucleotide polymorphisms (SNPs) located in 24 linkage groups (LGs). The total genetic length of the linkage map was 1,261.96 cM, and the length of each LG varied from 24.72 cM for LG02 to 117.53 cM for LG16, with an average length of 52.58 cM and an average SNP number of 286. Thirteen significant quantitative trait loci (QTLs) for sex determination were located on LG04, LG05, LG08, LG12, LG15, LG21, and LG23. An informative QTL cluster that included six QTLs was detected on LG12. However, one notable QTL, which accounted for 71.48% of the total phenotypic variation, was located in the region of 1.85 cM on LG05. In addition, 32 identified QTLs were related to growth, including body weight, body length, body height, and head length. The QTLs for these growth-related traits are located in 13 LG regions and have little effect on phenotypic variation. This high-density genetic linkage map will enable the fine-mapping of economic traits and support the future genome assembly of the largemouth bass. Additionally, our study will be useful for future selective culture of largemouth bass and could potentially be used in molecular-assisted breeding of largemouth bass for aquaculture.
Highlights
The largemouth bass, Micropterus salmoides, is a large carnivorous fish inhabiting freshwater rivers and lakes in North America (Bai et al, 2008)
The linkage map of the total genomic length was 1,261.96 cM, with the genetic length of each linkage groups (LGs) varying from 24.72 cM for LG2 to 117.53 cM for LG16, with an average length of 52.58 cM and an average single-nucleotide polymorphisms (SNPs) number of 286
We identified 13 significant quantitative trait locus (QTL), including 49 SNP loci for sex determination, which were distributed among seven LGs: LG04, LG05, LG08, LG12, LG15, LG21, and LG23
Summary
The largemouth bass, Micropterus salmoides, is a large carnivorous fish inhabiting freshwater rivers and lakes in North America (Bai et al, 2008). This species is widely cultivated in China because of characteristics such as strong temperature resistance, adaptability to new environments, and attractiveness as a food source. In 1983, the largemouth bass was first introduced into mainland China At present, it plays an indispensable role as a freshwater aquaculture species in China (Deng et al, 2011); more than 30 years after the establishment of largemouth bass farming, China has an annual output of approximately 500,000 tons. A largemouth bass species program needs to be established to improve its economic traits and sustain the development of the largemouth bass industry
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