草鱼出血病抗性基因的全基因组发掘

Hemorrhagic disease that induced by grass carp reovirus (GCRV) is a serious disease of grass carp, exploring disease-resistant genes in grass carp is important foundation for molecular breeding of disease-resistant strain. In our previous study, we found that abundant genetic diversity existed in grass carp populations and different disease resistance ability was observed in different families. The heritability of GCRV resistance traits was up to 0.63, which provided genetic basis for the molecular breeding of disease-resistant strain. Moreover, allele frequency analysis and genotype phenotype association analysis was carried out for several differential expressed genes that identified by transcriptome sequencing. After that, a disease-resistant gene was identified successfully, which provided technical support for the molecular breeding of disease-resistant strain. Based on these results, we want to explore the hemorrhagic disease-resistant genes in the whole genome of grass carp. A random mating population will be constructed by randomly mating female and male grass carp parents from different water systems. Two-way GCRV challenge method will be carried in order to obtain the death group and survival group samples precisely. Through genome structure analysis, the unique sequences in grass carp genome will be identified as reference for further study. At last, the samples from death group and survival group will be sequenced by next generation sequencing and analyzed by method similar to bulked segregant analysis (BSA) in order to identified genes that showed significant difference in allele frequency between death group and survival group, that is, hemorrhagic disease-resistant genes. The results of our study will provide important target genes for further study of genotype association analysis and molecular breeding of disease-resistant grass carp.

出血病是草鱼养殖中的重要病毒性病害，抗性相关基因的发掘是抗病品系分子选育的重要基础。我们的研究发现，草鱼群体存在丰富的遗传多样性，不同家系的抗病力存在差异，抗病性状的遗传力达到0.63，为抗病品系选育的可行性提供了理论依据；针对部分攻毒前后转录组差异表达基因，采用等位基因频率和基因型关联分析方法，成功筛选到一个抗性相关基因，为抗病品系分子选育的可行性提供了技术支撑。在此基础上，本项目拟进一步在全基因组范围内发掘出血病抗性相关基因。以不同水系来源的草鱼亲本，构建一个人工随机交配群体；采用双向病毒感染方法，分别获得存活组和死亡组实验材料；通过基因组的结构解析，甄别草鱼基因组中的唯一性序列；进行高通量DNA测序，采用类似集团分离分析方法，筛选在存活组和死亡组中等位基因频率呈现显著性差异的基因，即出血病抗性相关基因。本项目的研究成果，将为后续基因型关联分析和抗病品系分子选育提供重要的靶向基因。

草鱼是我国第一大淡水养殖鱼类，具有重要的经济价值。出血病是草鱼养殖中的重要病毒性病害，抗性相关基因的发掘是抗病草鱼品系分子选育的重要基础。本项目以不同水系来源的草鱼亲本为对象（6雄5雌），构建了一个具有遗传多样性的人工随机交配群体；通过采用双向病毒感染方法，对该随机交配群体进行病毒感染实验，分别获得了存活组和死亡组的DNA材料；通过对草鱼基因组的结构解析，获得了基因组中具有等位性和唯一性的1,899,822个SNP位点；利用高通量测序技术，对死亡/存活组的材料进行高通量DNA测序，并利用上述的SNP位点进行基因分型；通过卡方检验，对存活组和死亡组进行基因型频率的比较分析，获得了15个SNP位点的基因型频率在存活组和死亡组中存在明显的差异，这15个SNP位点涉及到15个基因，分布在8条染色体上，为出血病抗性基因的候选位点。本项目的研究成果为后续的草鱼抗病品种的分子选育奠定了坚实的基础。