Quantitative Trait Loci Mapping and Marker Identification for Low Salinity Tolerance Trait in the Swimming Crab (Portunus trituberculatus).

Jianjian Lv,Ping Liu,Jian Li,Dongfang Sun,Xingbin Ti,Deping Yan

doi:10.3389/fgene.2019.01193

Abstract

Low salinity is one of the most important abiotic factors that directly affect the abundance of the swimming crab, Portunus trituberculatus. Quantitative trait loci (QTL) mapping could be helpful in identifying the markers and genes involved in low salinity tolerance. In this study, two QTLs of low salt tolerance were mapped on linkage group 17 (LG17, 2.6–5.2 cM) based on a high-density linkage map. Ninety-five markers related to low salinity tolerance were identified via association analysis, and seventy-nine low salt-related candidate genes (including ammonium transport, aldehyde dehydrogenase, and glucosyltransferase) were screened from draft genome of the species via these markers. This represents the first report of QTL mapping for low salinity tolerance in the swimming crab, which may be useful to elucidate salinity adaptation mechanisms.

Highlights

The swimming crab, Portunus trituberculatus (Crustacea: Decapoda: Brachyura), is an important marine species for fisheries and aquaculture
On the basis of the high density linkage map, Two Quantitative trait loci (QTL) related to low salinity tolerance trait were detected by MapQTL 4.0 software, which were located on LG17 (2.6–5.2 cM) (Table 1 and Figure 1)
Each QTL interval contained two markers, and each marker contributed to phenotypic variance explained (PVE) of 14.8% with likelihoodratio statistic (LOD) value of 3.06 (Table 1)

Summary

Introduction

The swimming crab, Portunus trituberculatus (Crustacea: Decapoda: Brachyura), is an important marine species for fisheries and aquaculture. Due to its fast growth, P. trituberculatus has become one of the most important economic species for marine aquaculture (Ren and Pan, 2014). Salinity is one of the most important abiotic factors that directly affect the distribution and abundance of the swimming crab (Lv et al, 2013; Lv et al, 2015). Crabs are often exposed to low salinity stress due to rainstorms and water exchange, causing death and huge economic losses. Compared to growth, the heritability of salt tolerance traits is lower (Baoquan et al, 2010; Zheng et al, 2015). To elucidate the potential genetic mechanisms underlying salt tolerance traits, some scholars tried to explore related genes by comparative transcriptome (Xu and Liu, 2011; Lv et al, 2013), and hundreds of potential salt tolerance related genes have been identified involved in crucial processes, such as ion transport processes, amino acid metabolism and synthesis processes, proteolysis process and chitin metabolic

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