虾夷扇贝自交二代家系（F2）不衰退的遗传调控机理

Inbreeding is a widespread biological phenomenon both in plants and animals, which also has a dramatic effect on the survival of Patinopecten yessoensis, one of the most important economic shellfish species in northern China. In our previous study, inbred lines F2 were established by three hermaphrodites, produced by the same hermaphrodites parental Patinopecten yessoensis, and concluded that the surviving trait showed a significant depression only in F1, but not in F2. In this study, the genetic regulation mechanism of this phenomenon was explored from the omics level: at the genome level, the Miso-RAD libraries of selfing F1 and F2 generations were constructed, and the gene locus were screened, which related to avoiding inbreeding depression; at the transcriptome level, the key regulatory genes were identified, the network regulatory mechanism was analyzed by gene expression sequencing and genes co-expression network construction. This study intends to comprehensively utilize the omics technology and molecular biology methods to analyze the genetic mechanism of F2 generation without self-depression, for further understanding of inbreeding effects on the P. yessoensis and providing strong support for better breeding.

近交是动植物中广泛存在的一种生物学现象，近交效应对我国北方水产养殖中最重要经济的贝类之一的虾夷扇贝( Patinopecten yessoensis)的存活也产生着巨大的影响。本课题组前期利用1个虾夷扇贝雌雄同体的子代中继续出现的3个雌雄同体构建了自交系F2，并发现存活性状仅仅在F1代表现出显著的衰退，而在F2代中均不衰退。本研究从组学层面对这一现象的遗传调控机理进行探究：在基因组水平上构建自交F1、F2代Miso-RAD文库，筛查不衰退相关位点；在转录组水平上通过表达谱测序，及基因共表达网络鉴定调控关键基因，并解析其网络调控模式。本研究拟综合利用多组学技术和分子生物学研究手段，对自交F2代不衰退的遗传机理进行解析，以深入理解近交效应对虾夷扇贝影响的同时，为良种选育提供有力支持。

虾夷扇贝( Patinopecten yessoensis)为冷水性贝类，是我国北方水产养殖中最重要经济的贝类之一。近些年来，由于近交引起的种质退化被认为是导致虾夷扇贝养殖群体死亡频发的重要原因之一。本项目从虾夷扇贝系谱近交系数高达0.75的连续两代自交F2家系中发现了近交衰退的反例，在存活率和肌肉生长未发生F1代的衰退现象。通过基因组学手段筛查到了F2代近交不衰退的关键SNP位点523个，区间范围内定位到有注释的候选基因131个；通过成体期转录组分析，在3个不衰退F2代家系共有的500个差异基因中与F1代近交衰退表达相反的候选基因16个，通过基因共表达网络分析在关键模块的基因有HEXP、SBK1、SREBP1；通过幼虫期转录组分析，筛查到包括SREBP1在内的12个共有差异基因，其中9个差异基因都在关键M11模块。确定了SREBP1在近交效应中的关键调控地位，并利用chip-seq技术，SREBP1富集到的下游靶位点共注释到了51个靶基因，其中NNMT、TLR21、SRF为生长与抗逆相关基因。为近交效应的调控机理进行深入解析的同时，也为虾夷扇贝种质改良提供有力支撑。