Application of genetic markers to improve resistance to herpes virus in commercial oyster populations

背景：太平洋牡蛎(C.gias)是世界上最重要的水产养殖物种之一，但牡蛎疱疹病毒(OsHV)的暴发威胁着可持续生产，导致高死亡率。在养殖群体中，抗性存在很大的寄主遗传变异。因此，通过选择性育种提高存活率有可能成为疾病控制的主要组成部分。然而，英国的牡蛎生产还没有能力生产更多的抗性种群，因为贝类的结构化选择性繁殖计划还不存在。作为正在进行的BBSRC-NERC可持续水产养殖奖的一部分，罗斯林研究所、Cefas和爱丁堡基因组学开发了第一个牡蛎高密度单核苷酸多态性(SNP)阵列。同时，还成功地进行了实验室病毒挑战实验。这项试验中的抗性和敏感牡蛎正在进行基因分型，以绘制牡蛎基因组中的抗性基因座。主要的实际成果将是可以预测哪些牡蛎对这种疾病具有抵抗力的SNP标记。项目伙伴和挑战：英国缺乏对贝类的选择性育种给英国的生产带来了巨大的挑战(和机会)；即(1-短期)从对OsHV-1具有高抵抗力的亲本牡蛎中寻找和繁殖，(2-长期)转向管理良好的牡蛎选择性育种，以利用遗传变异来改善关键性状。罗斯林研究所将与Cefas和英国牡蛎孵化厂Guersey Sea Farm Ltd和Seasalt ShellFish Ltd合作应对这些挑战。他们还将与新西兰Cawthron研究所合作，后者在贝类繁殖和繁殖方面处于世界领先地位，但尚未在其育种计划中应用现代基因组工具。该项目直接促进了与“提高种群数量的育种和遗传学方法”和“监测和控制健康和疾病”有关的呼吁主题。目的和目的：该项目的主要目的是应用遗传标记在养殖环境中培育对牡蛎疱疹病毒具有更高抵抗力的牡蛎。拟议项目的具体目标是：(I)利用田间暴发期间商业牡蛎种群的样本和数据，验证与OsHV抗性相关的SNP标记。(Ii)在商业孵化场内建立利用亲本牡蛎进行分子标记辅助选择抗药性的程序。(Iii)在有谱系和性状记录的牡蛎种群中测试对OsHV抗性育种价值的基因组预测。(Iv)确定在牡蛎育种中使用遗传标记来提高抗病能力的最(成本)有效的方法。项目产出和影响：项目团队将与商业伙伴密切合作，提供有助于应对上述挑战的切实成果。对独立种群中田间暴发疫情中抗药性的SNP标记对发现的种群进行测试，将能够建立对OsHV抗药性的基因测试。这将应用于牡蛎水产养殖业，与商业孵化合作伙伴合作，并开发一种系统来对亲本牡蛎进行基因分型，以进行标记辅助选择。同时，将在不同的标记密度下评估基因组预测的效用(使用全基因组标记来预测育种价值)。这将产生一份关于利用遗传标记进行牡蛎抗病育种的最(成本)有效方法的报告。项目持续时间和成本：该项目将持续24个月，总成本为199,741 GB。

Background:Pacific oyster (C. gigas) is one of the most important aquaculture species in the world, but sustainable production is threatened by outbreaks of Oyster herpes virus (OsHV), which can cause high mortality rates. There is substantial host genetic variation in resistance within farmed stocks. Therefore, improvement of survival rates via selective breeding has the potential to form a major component of disease control. However, UK oyster production does not yet have the capacity to produce more resistant stocks, because structured selective breeding schemes for shellfish do not exist. As part of an ongoing BBSRC-NERC sustainable aquaculture award, the Roslin Institute, Cefas and Edinburgh Genomics have developed the first high density single nucleotide polymorphism (SNP) array for oysters. In parallel, a laboratory virus challenge experiment has been successfully performed. The resistant and susceptible oysters from this trial are being genotyped to map resistance loci in the oyster genome. The major practical outcome will be SNP markers that can predict which oysters are resistant to the disease.Project Partners and Challenges:The lack of selective breeding for shellfish in the UK presents significant challenges (and opportunities) for UK production; namely (1 - short term) to identify and breed from parent oysters with high resistance to OsHV-1, and (2 - long term) to move towards well-managed selective breeding of oysters to harness genetic variation to improve key traits. The Roslin institute will work with Cefas and UK oyster hatcheries Guersey Sea Farms Ltd and Seasalter Shellfish Ltd to address these challenges. They will also work with the Cawthron Institute (New Zealand), who are world leaders in shellfish breeding and reproduction, but do not yet apply modern genomic tools in their breeding programmes. The project directly contributes to the themes of the call relating to "Breeding and genetics approaches for stock enhancement" and "Monitoring and control of health and disease". Aims and Objectives:The primary aim of this project is to apply genetic markers to breed oysters with improved resistance to oyster herpes virus in the farm environment. The specific objectives of the proposed project are:(i) To verify SNP markers associated with OsHV resistance using samples and data from commercial oyster populations during field outbreaks.(ii) To establish a process within a commercial hatchery for marker-assisted selection for resistance using parental oysters. (iii) To test genomic prediction of breeding values for OsHV resistance in an oyster population with pedigree and trait records.(iv) To determine the most (cost) effective method of using genetic markers in oyster breeding to improve disease resistance.Project Outputs and Impacts:The project team will work closely with commercial partners to deliver tangible outputs that will help address the aforementioned challenges. Testing of SNP markers of resistance in field outbreaks in independent populations to the discovery population will enable a genetic test for OsHV resistance to be created. This will be applied to the oyster aquaculture industry by working with commercial hatchery partners, and developing a system to genotype parent oysters for marker-assisted selection. Concurrently, the utility of genomic prediction (use of genome-wide markers to predict breeding values) will be assessed at different marker densities. This will result in a report on the most (cost) effective means of using genetic markers to breed for disease resistance in oysters.Project Duration and Cost:The project will last 24 months and will have a total cost of £199,741.