大黄鱼抗白鳃病性状的遗传解析

Large yellow croaker (Larimichthys crocea) is the largest aquaculture species in terms of annual production among sea fish in China. In recent years, the viral white-gill syndrome (VWGS) has become the most damaging infectious disease and caused considerable economic loss in the large yellow croaker, with very high average incidence rate and cumulative mortality rate. Currently, no treatment has been proved to be effective to the VWGS. Therefore, selection of the VWGS-resistance populations is the most effective and fundamental solution in fighting against this disease. The proposal intend to map the QTL underlying the resistance to VWGS in the large yellow croaker using the low-coverage resequencing strategy in a challenged population and case-control populations sampled from aquaculture farms. We will further fine-map and identify the causative genes/mutations located in the major QTLs using eQTL analysis and ATAC-seq, and finally dissect the gene mechanisms associated with the causative mutations with the help of molecular analysis, such as ASE analysis, overexpression, RNAi and ChIP. The implement of this proposal will identify the causative genes and mutations underlying the genetic basis of VWGS resistance, dissect the gene mechanisms at the gene regulation level, and provide molecular markers for marker-assisted breeding for the large yellow croaker. Furthermore, the results can provide the precise gene targets for disease-resistance breeding with gene editing in the near future.

大黄鱼是目前我国养殖量最大的海水鱼，近年来由病毒感染引发的白鳃病已成为发病率和致死率最高、危害最严重的病害，造成了巨大的经济损失，目前尚无有效的防治办法。培育抗病品种是解决该病害问题的有效和根本途径。本项目拟从自然发病的养殖群体和攻毒实验群体采集抗性和易感个体作为实验材料，进行全基因组低深度重测序，通过全基因组关联分析(GWAS)，结合eQTL分析、染色质开放区定位(ATAC-seq)等技术，精细定位白鳃病抗性位点，筛选具有育种价值的分子标记；同时挖掘导致抗病力差异的主效基因/因果突变，结合等位基因表达不平衡(ASE)、过表达、RNAi、免疫共沉淀等技术阐释其作用机制。本项目预期将获得可直接用于抗病品种选育的分子标记，鉴定出导致个体间对白鳃病抗病力差异的主效基因与因果突变，并在基因表达调控水平解析其作用机制，为最终阐明其作用机理奠定基础，也为后续通过基因编辑更有效培育抗病良种提供基因靶点。

大黄鱼是我国养殖量最大的海水鱼，近年来由病毒感染引发的白鳃病已成为发病率和致死率最高、危害最严重的病害。本研究收集到2000多尾大黄鱼的白鳃病患病个体和健康个体，利用全基因组低深度重测序技术进行所有个体的测序，挖掘出突变位点并开展了GWAS定位，挖掘了主效基因位点；在采集的健康群体中，选取了81尾个体的脾脏进行转录组测序，并开展了大黄鱼脾脏组织的表达QTL（eQTL）研究，发现了大量与免疫基因表达调控相关的变异位点；并对部分显著位点进行实验验证工作。对大黄鱼进行了肝脏和性腺组织的ATAC-seq分析，系统发掘了其全基因组范围的调控元件，并结合其他物种进行保守性分析，为分析调控区的突变如何影响大黄鱼的抗病机制提供了必要的基础。针对GWAS的定位结果，我们进行了大量的遗传突变筛选，获得了与抗病表型相关的单碱基变异位点；我们就较好的候选基因进行了基因功能研究。本研究在基因组、转录组和基因表达调控层面对大黄鱼抗白鳃病的遗传基础进行了解析，找到的显著突变位点可作为遗传选育靶点。此外，研究中发现的一些基因及其表达调控模式为今后大黄鱼的抗病选育提供了重要基础。