Breseghello Flavio, Sorrells Mark E
Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853, USA.
Genetics. 2006 Feb;172(2):1165-77. doi: 10.1534/genetics.105.044586. Epub 2005 Aug 3.
Association mapping is a method for detection of gene effects based on linkage disequilibrium (LD) that complements QTL analysis in the development of tools for molecular plant breeding. In this study, association mapping was performed on a selected sample of 95 cultivars of soft winter wheat. Population structure was estimated on the basis of 36 unlinked simple-sequence repeat (SSR) markers. The extent of LD was estimated on chromosomes 2D and part of 5A, relative to the LD observed among unlinked markers. Consistent LD on chromosome 2D was <1 cM, whereas in the centromeric region of 5A, LD extended for approximately 5 cM. Association of 62 SSR loci on chromosomes 2D, 5A, and 5B with kernel morphology and milling quality was analyzed through a mixed-effects model, where subpopulation was considered as a random factor and the marker tested was considered as a fixed factor. Permutations were used to adjust the threshold of significance for multiple testing within chromosomes. In agreement with previous QTL analysis, significant markers for kernel size were detected on the three chromosomes tested, and alleles potentially useful for selection were identified. Our results demonstrated that association mapping could complement and enhance previous QTL information for marker-assisted selection.
关联作图是一种基于连锁不平衡（LD）检测基因效应的方法，在分子植物育种工具开发中可作为对数量性状基因座（QTL）分析的补充。在本研究中，对95个软质冬小麦品种的选定样本进行了关联作图。基于36个不连锁的简单序列重复（SSR）标记估计群体结构。相对于在不连锁标记间观察到的LD，估计了2D染色体和5A部分区域的LD程度。2D染色体上一致的LD小于1厘摩（cM），而在5A染色体的着丝粒区域，LD延伸约5 cM。通过混合效应模型分析了2D、5A和5B染色体上62个SSR位点与籽粒形态和制粉品质的关联，其中亚群被视为随机因素，测试的标记被视为固定因素。采用排列法调整染色体内部多重检验的显著性阈值。与先前的QTL分析一致，在测试的三条染色体上检测到了与籽粒大小相关的显著标记，并鉴定出了可能对选择有用的等位基因。我们的结果表明，关联作图可以补充和增强先前用于标记辅助选择的QTL信息。
