Construction of an improved linkage map of diploid alfalfa (Medicago sativa)
Construction of an improved linkage map of diploid alfalfa (Medicago sativa)
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DOI：
10.1007/s001220051335
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发表时间：
2000-03-01
影响因子：
5.4
通讯作者：
Kiss, GB
中科院分区：
文献类型：
--
作者：
Kaló, P;Endre, G;Kiss, GB
通过对137株植物个体的F - 2群体中800多个遗传标记的遗传分析，绘制出了二倍体（2n = 2x = 16）苜蓿的改良遗传图谱。该F - 2分离群体来自紫花苜蓿亚种准镰荚苜蓿（Medicago sativa ssp. quasifalcata）与蓝花苜蓿亚种（Medicago sativa ssp. coerulea）杂交的一个自交F - 1杂种个体。这个作图群体与我们之前构建苜蓿遗传图谱所使用的群体相同。利用最大似然方程和相关计算机程序进行了遗传分析。目前形式的苜蓿改良遗传图谱在8个连锁群中包含868个标记（4个形态标记、12个同工酶标记、26个种子蛋白标记、216个RFLP标记、608个RAPD标记和2个特异性PCR标记）。其中80个标记是已知基因，包括2个先前已进行细胞学定位的基因，即rDNA和β - 微管蛋白基因座。该遗传图谱覆盖754厘摩（cM），平均标记密度为0.8个/cM。物理距离和遗传距离之间的相关性约为每厘摩1000 - 1300千碱基对。在该图谱中，连锁群6、7和8上一些标记的连锁关系与先前发表的图谱不同。这种差异的原因是，表现出偏分离（以杂合个体数量极多为特征）的标记的遗传连锁人为地连接了原本不连锁的遗传区域。为了克服过多杂合基因型对重组率的不利影响，我们使用了最近描述的最大似然公式和彩色图谱绘制法，这使我们能够排除误导性的连锁关系，并更精确地估计遗传距离。
An improved genetic map of diploid (2n=2x=16) alfalfa has been developed by analyzing the inheritance of more than 800 genetic markers on the F-2 population of 137 plant individuals. The F-2 segregating population derived from a self-pollinated F-1 hybrid individual of the cross Medicago sativa ssp. quasifalcata x Medicago sativa ssp, coerulea. This mapping population was the same one which had been used for the construction of our previous alfalfa genetic map. The genetic analyses were performed by using maximum-likelihood equations and related computer programs. The improved genetic map of alfalfa in its present form contains 868 markers (four morphological, 12 isozyme, 26 seed protein, 216 RFLP, 608 RAPD and two specific PCR markers) in eight linkage groups. Of the markers 80 are known genes, including 2 previously cytologically localized genes, the rDNA and the beta-tubulin loci. The genetic map covers 754 centimorgans (cM) with an average marker density of 0.8/cM. The correlation between the physical and genetic distances is about 1000-1300 kilobase pairs per centi-Morgan. In this map, the linkage relationships of some markers on linkage groups 6, 7, and 8 are different from the previously published one. The cause of this discrepancy was that the genetic linkage of markers displaying distorted segregation (characterized by an overwhelming number of heterozygous individuals) had artificially linked genetic regions that turned out to be unlinked. To overcome the disadvantageous influence of the excess number of heterozygous genotypes on the recombination fractions. we used recently described maximum-likelihood formulas and colormapping, which allowed us to exclude the misleading linkages and to estimate the genetic distances more precisely.