Ripol M I, Churchill G A, da Silva J A, Sorrells M
Department of Plant Breeding and Biometry, Cornell University, Ithaca, NY 14853, USA.
Gene. 1999 Jul 22;235(1-2):31-41. doi: 10.1016/s0378-1119(99)00218-8.
Many plant species of agriculture importance are polyploid, having more than two copies of each chromosome per cell. In this paper, we describe statistical methods for genetic map construction in autopolyploid species with particular reference to the use of molecular markers. The first step is to determine the dosage of each DNA fragment (electrophoretic band) from its segregation ratio. Fragments present in a single dose can be used to construct framework maps for individual chromosomes. Fragments present in multiple doses can often be used to link the single chromosome maps into homologous groups and provide additional ordering information. Marker phenotype probabilities were calculated for pairs of markers arranged in different configurations among the homologous chromosomes. These probabilities were used to compute a maximum likelihood estimator of the recombination fraction between pairs of markers. A likelihood ratio test for linkage of multidose markers was derived. The information provided by each configuration and power and sample size considerations are also discussed. A set of 294 RFLP markers scored on 90 plants of the species Saccharum spontaneum L. was used to illustrate the construction of an autopolyploid map. Previous studies conducted on the same data revealed that this species of sugar cane is an autooctaploid with 64 chromosomes arranged into eight homologous groups. The methodology described permitted consolidation of 54 linkage groups into ten homologous groups.
许多具有农业重要性的植物物种都是多倍体，每个细胞中每条染色体都有两份以上的拷贝。在本文中，我们描述了在同源多倍体物种中构建遗传图谱的统计方法，特别提及了分子标记的使用。第一步是根据其分离比例确定每个DNA片段（电泳条带）的剂量。单剂量存在的片段可用于构建单个染色体的框架图谱。多剂量存在的片段通常可用于将单个染色体图谱连接成同源组，并提供额外的排序信息。计算了同源染色体间以不同构型排列的标记对的标记表型概率。这些概率用于计算标记对之间重组率的最大似然估计值。推导了多剂量标记连锁的似然比检验。还讨论了每种构型提供的信息以及功效和样本量的考虑因素。利用在90株甘蔗（Saccharum spontaneum L.）上评分的一组294个RFLP标记来说明同源多倍体图谱的构建。此前对相同数据进行的研究表明，这种甘蔗是一种同源八倍体，有64条染色体，排列成八个同源组。所描述的方法允许将54个连锁群合并为十个同源组。
