人工选择压力下凡纳滨对虾生长速度与繁殖性能的权衡机制研究

The fecundity of parent shrimp and growth rate of seedling shrimp are important traits to determine the economic benefits of nursery and farmer. Many results showed that the strains with high growth rate had lower fecundity and the strains with high fecundity had lower growth rate. Life history theory holds that this is the result of energy trade-off under the pressure of artificial selection, but the nutritional biochemistry, quantitative genetic evidence and molecular mechanism of energy trade-off are not clear. This has become a key issue in determining the breeding strategies (multi-trait combined breeding or specialized strain crossbreeding) and carrying out molecular-assisted breeding. The project aims to set a different selection index of different weighted proportional for the growth rate and fecundity, and design three groups of mating system (weighted proportional for growth rate and fecundity were 100%: 0%, 50%: 50% and 0%: 100%, respectively). Establish of multitudinous families and test breeding population biochemical index of gonad, growth rate and fecundity performance. Qualitative and quantitative analysis of the genetic relationship between them, and determine the effect of artificial selection on growth rate and fecundity performance. A number of time nodes were selected for the three breeding groups, and the difference genes of growth rate and fecundity were screened from the perspective of transcriptomics. To analyze the molecular genetic trade-off mechanism of growth rate and fecundity in energy harvesting, so as to improve the scientific and stability of Penaeus vannamei breeding and the ultimate goal is to speed up the breeding process.

种虾繁殖力和苗种生长速度是决定育苗场和养殖户经济效益的重要性状。实践表明生长速度快的品系繁殖力较低，繁殖力较高的品系生长速度较慢。生命进化史理论认为，这是动物在人工选择压力下能量权衡分配的结果，然而能量权衡分配的营养生化学、数量遗传学证据和分子机制尚不明确。这已成为确定育种策略（多性状复合选择或专门化品系杂交），开展分子辅助育种亟待解决的问题。本项目拟对生长速度和繁殖力的选择指数设置不同加权比，设计3组配种方案（生长速度：繁殖力加权比为100%:0%，50%:50%和0%:100%），大规模建立家系，测试育种群体性腺生化指标、生长速度和繁殖力，定性定量分析三者间的遗传相关关系，明确人工选择对生长速度和繁殖力影响程度；对3个选育系选择多个时间节点，从转录组学角度系统筛选控制生长速度和繁殖力的差异基因，解析生长与繁殖性状在能量获取方面的分子遗传机制，从而提高凡纳滨对虾选育的科学性及稳定性。

本项目通过设置不同选择指数构建生长速度和繁殖力差异群体，并对不同群体开展生长速度和繁殖力相关测试，研究发现经过人工选择的不同生长速度和繁殖力差异的群体，其繁殖期生长速度与繁殖性状（产卵时间间隔）是相互权衡的，而早期生长速度与繁殖性状（产卵时间间隔）则不是相互权衡的关系。通过对不同品系家系的生长和繁殖测试发现，S品系生长速度最快，繁殖力最低，E品系其生长速度相对较慢，但是其繁殖力最高，因此说明在凡纳滨对虾生长至8-12月龄时，其生长速度与繁殖性状存在权衡关系。而对于营养生化指标的研究发现，高繁殖力对虾（产卵时间间隔小的对虾），其甘油三酯与卵黄蛋白积累的更多，因此繁殖期生长速度与营养生化指标含量也呈权衡关系，因此，性腺营养生化指标可以作为判断对虾繁殖力高低的标准。本项目对于选育生长速度快、高繁殖力对虾的遗传育种工作具有重要意义。