发展适合于同源四倍体物种的数量遗传模型与分析方法

Up to 80% of higher plants have experienced a status of polyploidy in their evolutionary histories. Many evolutionarily and agriculturally important species still have a polyploidy genome. The most significant example of these is the cultivated autotetraploid potato, the third most important food crop. Although genetical and genomic analyses have been routinely practiced in diploids, the relevant work in autotetraploids lags far behind the advancement. This may be largely attributed to the lack or poorness in advancement in theory and methodology for the analyses in the autotetraploid species. Quantitative genetic models are the basis for various quantitative genetic studies in both basic and applied aspects. Theory and methods are well established for creating quantitative genetic models and have facilitated advancement of the subject Quantitative Genetics in diploid species. However, these are still in infancy in polyploid species, particularly autotetraploids. This research is designed to fill in this scientific gap, and proposed to develop theory and methods for quantitative genetic models that is appropriate for quantitative genetic analyses in autotetraploid species. In addition, we will develop appropriate statistical methods for exploring feasibility of estimation of the model parameters and for estimating the model parameters. The theory and methods to be developed in the proposed research will take the key features of tetrasomic inheritance of gene segregation and recombination into account and will ensure several idealized statistical properties such as orthogonality between genetic values of different genotypes at single or two quantitative trait loci (QTL). We proposed to test for reliability and utility of the theory and methods to be developed through intensive computer simulation studies and implementation of analysis with real experimental data from autotetraploid potato. Conduct of the research proposed here will lay the scientific base for quantitative genetic studies and enable various quantitative genetic analyses to be performed on the rigorous basis in autotetraploid species. Moreover, accomplishment of the research objectives will not only enrich the subject of Quantitative Genetics but also facilitate genetic breeding in autotetraploid crops and aquaculture animals.

80%以上的高等植物在其进化过程中存在多倍性。许多重要的物种也是多倍体，其中最有代表性的是全球第三大粮食作物- - 四倍体栽培马铃薯。尽管二倍体遗传和基因组分析已成为常规手段，但由于理论和方法学研究在同源四倍体物种中的严重滞后，许多相关研究几乎为空白。数量遗传学模型的理论和方法在二倍体物种中已成熟建立并广泛应用，但在多倍体尤其是同源四倍体中类似的研究工作才刚刚起步。本研究将建立适合于同源四倍体物种数量遗传分析的数量遗传学模型，并发展相应的统计学方法用以模型参数估计。本项目拟建立的理论模型以及相应的统计分析方法将严格兼顾四体遗传基因分离和重组的主要特征，并将保证模型所定义的不同基因效应具备理想的统计性质，如正交性。我们将通过开展计算机随机模拟研究和分析同源四倍体马铃薯实验数据，对理论分析与方法学研究的结果加以验证。本研究将为同源四倍体这一重要物种的数量遗传分析填补一个科学空白。

数量遗传模型是连接控制数量性状的基因的遗传效应与该数量性状表型的统计学模型，是任何数量遗传分析最重要的理论基础之一。数量遗传学在二倍体物种中已发展了成熟的科学理论与方法学，而在多倍体特别是同源多倍体，例如同源四倍体物种中却仍处于起步阶段。其主要原因是相对于二倍体物种，同源多倍体物种遗传的复杂性。. 本研究以同源四倍体物种的某一随机交配自然群体，或由任意两个数量性状表型差异显著的同源四倍体亲本杂交所产生的分离群体为对象，在充分考虑四体遗传基因分离与重组的主要特征基础上，构建了该群体中一个或两个位点QTL遗传效应的、具有正交性质的统计学模型，并发展了相关模型参数估计的统计方法。虽然基于相同的统计学原理，共享相似的统计学性质，但是对于不同遗传结构的群体（如本研究针对的自然群体以及人工设计交配产生的分离群体），我们已经建立的数量遗传学模型具有不同的表示形式。我们通过开展计算机随机模拟研究，对理论分析与方法学研究的结果进行了验证。模拟研究证明了将双减数系数合理引入同源四倍体数量遗传模型的构建并准确估计该系数，对于同源四倍体数量遗传分析以及遗传效应参数估计都至关重要。. 本研究为同源四倍体物种多基因数量性状的遗传分析这一重要的研究领域奠定了科学基础并提供了重要的分析工具。

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