多鳞[鱼喜](Sillago sihama)高密度遗传连锁图谱构建及生长性状QTL定位分析

CONSTRUCTION OF A HIGH-DENSITY GENETIC LINKAGE MAP AND QTL DETECTION OF GROWTH TRAITS OF SILVER SILLAGO(SILLAGO SIHAMA)

为构建多鳞[鱼喜](Sillago sihama)遗传连锁图谱并鉴定生长等重要经济性状数量性状位点(QTL),实验通过基因分型测序(GBS)技术对163个多鳞[鱼喜]个体(2个亲本和161个全同胞家系F1代)进行测序及标记分型,并通过复合区间定位法对该物种的体重、体高、体厚、眼径、体长和背鳍前长6个生长性状进行QTL定位分析。结果显示,多鳞[鱼喜]首张高密度遗传连锁图谱全长2 154.803 c M,标记间平均遗传距离0.455 c M,共有4 735个SNP标记分配到24个连锁群。QTL定位分析结果发现在6个生长性状中共检测到20个生长显著相关QTL位点,分布在8个连锁群上,单个QTL的LOD值范围为3.02~4.23,可解释的表型变异范围为0.14%~8.42%。其中,在连锁群LG08聚集了8个生长性状显著相关的QTL。通过对候选QTL区间内的基因进行功能注释,共筛选到了19个潜在生长调控相关基因,包含igf1、igf2、sstr5、sst1a、tgfbr2、gas1、igfals、gfg6、gfg20、bmp7、kdm5c、tti1以及rbm10等。实验获得的遗传标记及相关候选基因是多鳞[鱼喜]生长相关性状标记辅助选择(MAS)的有用基因资源,为进一步研究鱼类生长调控机制提供了更多的理论依据。

Construction of high-density genetic map and quantitative trait loci(QTL) mapping are powerful tools for identifying genetic markers and candidate genes that may be responsible for such polygenic trait as growth. The first SNP-based high-density genetic linkage map was constructed by sequencing 163 silver sillago(Sillago sihama) individuals(2 parents and 161 F1 offspring) according to a genotyping-by-sequencing(GBS) method. The consensus map spanned 2 154.803 cM, on average marker interval of 0.455 cM. In total, 4 735 SNPs were assigned to 24 linkage groups(LGs).Then, the QTL of 6 growth related traits was mapped via composite interval mapping(CIM), including body weight, body length, body thickness, body height, pre-dorsal length, and eye diameter. Twenty significant QTLs were identified on 8LGs and explained 0.14%~8.42% of the phenotypic variance. The logarithm of odds(LOD) value ranged from 3.02 to 4.23.Specially, 8 QTLs were distributed on one linkage group(LG08), and the regions showed overlapping on LG08. Through the functional annotation of the genes in the candidate QTL interval, 19 potential growth-related genes were screened,including igf1, igf2, sstr5, sst1a, tgfbr2, gas1, igfals, gfg6, gfg20, bmp7, kdm5c, tti1, and rbm10. These genetic markers and candidate genes are useful genomic resources for marker-assisted selection(MAS) in silver sillago and the QTLs are useful tools for growth mechanism analysis of this fish.