Abstract
Simple SummarySlow growth and germplasm degradation have restricted the sustainable commercial development of the sea cucumber industry. To analyze the genetic mechanism of growth traits of sea cucumbers, we constructed a high-density genetic linkage map based on single nucleotide polymorphism (SNP) molecular markers and performed a quantitative trait loci (QTL) mapping analysis. We annotated a critical candidate gene related to growth traits and explored mRNA expression levels. The results showed that the gene was significantly highly expressed during the larval developmental stages. These results can be used to genetically improve the growth traits of sea cucumbers.Genetic linkage maps have become an indispensable tool for genetics and genomics research. Sea cucumber (Apostichopus japonicus), which is an economically important mariculture species in Asia, is an edible echinoderm with medicinal properties. In this study, the first SNP-based high-density genetic linkage map was constructed by sequencing 132 A. japonicus individuals (2 parents and 130 offspring) according to a genotyping-by-sequencing (GBS) method. The consensus map was 3181.54 cM long, with an average genetic distance of 0.52 cM. A total of 6144 SNPs were assigned to 22 linkage groups (LGs). A Pearson analysis and QTL mapping revealed the correlations among body weight, body length, and papillae number. An important growth-related candidate gene, protein still life, isoforms C/SIF type 2 (sif), was identified in LG18. The gene was significantly highly expressed during the larval developmental stages. Its encoded protein reportedly functions as a guanine nucleotide exchange factor. These results would facilitate the genetic analysis of growth traits and provide valuable genomic resources for the selection and breeding of new varieties of sea cucumbers with excellent production traits.
Highlights
IntroductionSea cucumber (Apostichopus japonicus) is an important edible aquaculture species in
Sea cucumber (Apostichopus japonicus) is an important edible aquaculture species inEast Asia because of its considerable medicinal value
The substantial limitations of traditional breeding methods have led to a greater focus on improving traits via molecular marker-assisted selection (MAS)
Summary
Sea cucumber (Apostichopus japonicus) is an important edible aquaculture species in. East Asia because of its considerable medicinal value. In 2020, more than 171,000 tons of sea cucumber were produced from a farming area of 246,745 hectares. The cultivation of sea cucumber has become one of the major mariculture industries in China. Increases in the scale of sea cucumber farming have highlighted specific problems, including germplasm degradation, slow growth, and frequent diseases, of which slow growth is one of the most prominent problems. Enhancing sea cucumber germplasm and cultivating new varieties with improved traits (e.g., rapid growth) are critical for sustainable commercial production. The substantial limitations of traditional breeding methods have led to a greater focus on improving traits via molecular marker-assisted selection (MAS)
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