Correa Katharina, Lhorente Jean P, López María E, Bassini Liane, Naswa Sudhir, Deeb Nader, Di Genova Alex, Maass Alejandro, Davidson William S, Yáñez José M
Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av Santa Rosa 11735, Santiago, Chile.
Aquainnovo, Talca 60, Puerto Montt, Chile.
BMC Genomics. 2015 Oct 24;16:854. doi: 10.1186/s12864-015-2038-7.
Pisciricketssia salmonis is the causal agent of Salmon Rickettsial Syndrome (SRS), which affects salmon species and causes severe economic losses. Selective breeding for disease resistance represents one approach for controlling SRS in farmed Atlantic salmon. Knowledge concerning the architecture of the resistance trait is needed before deciding on the most appropriate approach to enhance artificial selection for P. salmonis resistance in Atlantic salmon. The purpose of the study was to dissect the genetic variation in the resistance to this pathogen in Atlantic salmon.
2,601 Atlantic salmon smolts were experimentally challenged against P. salmonis by means of intra-peritoneal injection. These smolts were the progeny of 40 sires and 118 dams from a Chilean breeding population. Mortalities were recorded daily and the experiment ended at day 40 post-inoculation. Fish were genotyped using a 50K Affymetrix® Axiom® myDesignTM Single Nucleotide Polymorphism (SNP) Genotyping Array. A Genome Wide Association Analysis was performed on data from the challenged fish. Linear regression and logistic regression models were tested.
Genome Wide Association Analysis indicated that resistance to P. salmonis is a moderately polygenic trait. There were five SNPs in chromosomes Ssa01 and Ssa17 significantly associated with the traits analysed. The proportion of the phenotypic variance explained by each marker is small, ranging from 0.007 to 0.045. Candidate genes including interleukin receptors and fucosyltransferase have been found to be physically linked with these genetic markers and may play an important role in the differential immune response against this pathogen.
Due to the small amount of variance explained by each significant marker we conclude that genetic resistance to this pathogen can be more efficiently improved with the implementation of genetic evaluations incorporating genotype information from a dense SNP array.
鲑鱼立克次氏体是鲑鱼立克次氏体综合征（SRS）的病原体，该综合征影响鲑鱼品种并造成严重经济损失。抗病性的选择性育种是控制养殖大西洋鲑鱼中SRS的一种方法。在决定增强大西洋鲑鱼对鲑鱼立克次氏体抗性的人工选择的最合适方法之前，需要了解抗性性状的结构。本研究的目的是剖析大西洋鲑鱼对这种病原体抗性的遗传变异。
通过腹腔注射对2601尾大西洋鲑幼鱼进行鲑鱼立克次氏体的实验性攻毒。这些幼鱼是来自智利养殖群体的40尾雄鱼和118尾雌鱼的后代。每天记录死亡率，实验在接种后第40天结束。使用50K Affymetrix® Axiom® myDesignTM单核苷酸多态性（SNP）基因分型阵列对鱼进行基因分型。对攻毒鱼的数据进行全基因组关联分析。测试了线性回归和逻辑回归模型。
全基因组关联分析表明，对鲑鱼立克次氏体的抗性是一个中度多基因性状。在染色体Ssa01和Ssa17上有5个SNP与所分析的性状显著相关。每个标记解释的表型变异比例很小，范围从0.007到0.045。已发现包括白细胞介素受体和岩藻糖基转移酶在内的候选基因与这些遗传标记存在物理连锁，并且可能在针对这种病原体的差异免疫反应中起重要作用。
由于每个显著标记解释的变异量较小，我们得出结论，通过实施纳入来自密集SNP阵列的基因型信息的遗传评估，可以更有效地提高对这种病原体的遗传抗性。
