Aslam Muhammad Luqman, Carraro Roberta, Sonesson Anna Kristina, Meuwissen Theodorus, Tsigenopoulos Costas S, Rigos George, Bargelloni Luca, Tzokas Konstantinos
Nofima, Tromsø, Norway.
University of Padova, Padua, Italy.
Front Genet. 2020 Dec 22;11:594770. doi: 10.3389/fgene.2020.594770. eCollection 2020.
Gilthead sea bream () belongs to a group of teleost which has high importance in Mediterranean aquaculture industry. However, industrial production is increasingly compromised by an elevated outbreak of diseases in sea cages, especially a disease caused by monogeneans parasite This parasite mainly colonizes gill tissues of host and causes considerable economical losses with mortality and reduction in growth. The aim of current study was to explore the genetics of host resistance against and investigate the potential for genomic selection to possibly accelerate genetic progress. To achieve the desired goals, a test population derived from the breeding nucleus of Andromeda Group was produced. This experimental population was established by crossing of parents mated in partial factorial crosses of ∼8 × 8 using 58 sires and 62 dams. The progeny obtained from this mating design was challenged with using a controllable cohabitation infection model. At the end of the challenge, fish were recorded for parasite count, and all the recorded fish were tissue sampled for genotyping by sequencing using 2b-RAD methodology. The initial (before challenge test) and the final body weight (after challenge test) of the fish were also recorded. The results obtained through the analysis of phenotypic records ( = 615) and the genotypic data ( = 841, 724 offspring and 117 parents) revealed that the resistance against this parasite is lowly heritable ( = 0.147 with pedigree and 0.137 with genomic information). We observed moderately favorable genetic correlation ( = -0.549 to -0.807) between production traits (i.e., body weight and specific growth rate) and parasite count, which signals a possibility of indirect selection. A locus at linkage group 17 was identified that surpassed chromosome-wide Bonferroni threshold which explained 22.68% of the total genetic variance, and might be playing role in producing genetic variation. The accuracy of prediction was improved by 8% with genomic information compared to pedigree.
金头鲷（）属于硬骨鱼纲，在地中海水产养殖业中具有重要地位。然而，海水网箱中疾病的高发日益影响着其工业化生产，尤其是由单殖吸虫寄生虫引起的疾病。这种寄生虫主要寄生于宿主的鳃组织，会导致死亡率上升和生长减缓，造成巨大的经济损失。本研究旨在探索宿主对该寄生虫的抗性遗传学，并研究基因组选择加速遗传进展的潜力。为实现这些目标，构建了一个来自仙女座集团育种核心群的测试群体。该实验群体通过约8×8的部分析因杂交交配产生，使用了58个父本和62个母本。通过可控的共居感染模型，将该交配设计获得的后代用该寄生虫进行攻毒。攻毒结束时，记录鱼的寄生虫数量，并对所有记录的鱼进行组织采样，采用2b-RAD方法通过测序进行基因分型。同时记录鱼的初始体重（攻毒试验前）和最终体重（攻毒试验后）。通过对表型记录（=615）和基因型数据（=841，724个后代和117个亲本）的分析发现，对这种寄生虫的抗性遗传力较低（系谱估计为0.147，基因组信息估计为0.137）。我们观察到生产性状（即体重和特定生长率）与寄生虫数量之间存在中等程度的负遗传相关性（=-0.549至-0.807），这表明存在间接选择的可能性。在连锁群17上鉴定出一个位点，其超过了全染色体范围的Bonferroni阈值，解释了22.68%的总遗传方差，可能在产生遗传变异中发挥作用。与系谱相比，基因组信息使预测准确性提高了8%。
