Argopecten属扇贝种间杂交后代的育性决定机制

Interspecific hybrids between Argopecten scallops exhibited significant heterosis in growth. However, it has been hard to produce hybrid seeds at large scales from these hermaphroditic animals. This project aims to construct the first three-line breeding system including the male sterile line, maintainer line and restorer line, in the aquatic animals using the male sterile/female fertile scallops previously found in the F1 hybrids between the Argopecten scallops. Using the next-generation sequencing techniques, the female fertility determining factors will be screened by comparing the transcriptomes of the half-sibling families with different female fertility, the male sterility determining factors will be determined by comparing the transcriptomes of the male sterile line and its maintainer line, and the maintainer factors and restorer factors will be determined by comparing the trascriptomes of the maintainer line and restorer lines of the same male sterile line. Based on these results, the determining mechanisms of the interspecifc hybrids between Argopecten scallops will be explored and the corresponding molecular markers will be screened for their future utilization in marker-assisted selection in three-line breeding systems.

Argopecten属扇贝种间杂交后代表现出极显著的杂种优势，但由于该属扇贝均为雌雄同体，因此难以进行大规模杂交制种。本项目拟利用申请者前期从Argopecten属扇贝的种间杂交一代中发现的雄性不育且雌性可育的个体，构建水产动物中的首个包括雄性不育系、保持系和恢复系的三系配套育种体系；采用下一代测序技术，通过比较雌性可育和雌性不育杂交一代半同胞系的转录组确定其雌性育性决定因子，通过比较雄性不育系及其保持系的转录组确定致雄性不育因子，通过比较同一雄性不育系的保持系和恢复系的转录组确定雄性不育保持因子和雄性育性恢复因子，从而探讨Argopecten属扇贝杂交后代的育性决定机制，并筛选相应的分子标记用于该属扇贝的三系配套系分子标记辅助育种。

课题组在前期的研究中发现，紫扇贝与海湾扇贝杂交一代的大部分个体雄性不育而且雌性也不育，但是约2-5%的家系表现为雄性不育雌性可育现象，可以与紫扇贝或海湾扇贝回交，所培育的回交后代表现为雄性不育/雌性可育或雌雄同体，为此本项目旨在利用Argopecten属扇贝种间杂交后代中的雄性不育个体，构建遗传背景相关的雄性不育系、保持系和恢复系，利用下一代测序技术，通过比较不同家系的转录组，找到与扇贝杂交后代育性相关的主要基因，初步阐明Argopecten属扇贝种间杂交后代的育性决定机制，并进一步筛选相关的分子标记，用于Argopecten属扇贝三系配套系的分子标记辅助育种。本项目构建了大量具有极其显著生长优势的雄性不育的紫扇贝与海湾扇贝杂交一代家系；首次完成了紫扇贝和海湾扇贝两个亚种的基因组测序和高质量组装，从而为紫扇贝与两种海湾扇贝亚种杂交后代的性状研究提供了必需的参考基因组；建立了紫扇贝与海湾扇贝杂交一代及其亲本的转录组的比较分析方法，并通过对杂交扇贝性腺发育、高低温和弧菌处理的转录组响应分析进行了验证，为杂交扇贝重要性状决定机制研究打下了技术方法基础；利用获得的杂交一代雄性不育材料对杂交扇贝的雄性不育决定机制进行了解析，初步获得了与雄性不育决定相关的部分基因。结果表明，杂交一代的雄性不育特性的调控可能与性别分化、类固醇生物合成和泛素化修饰通路等代谢途径有关，转录组分析和qPCR结果均表明Sex comb on midleg-like protein 2和Sex-determining protein fem-1等基因可能在杂交一代的雄性不育的调控中起到关键作用。