Khrustaleva L I, de Melo P E, van Heusden A W, Kik C
Plant Research International, Wageningen University and Research Center, The Netherlands.
Genetics. 2005 Mar;169(3):1673-85. doi: 10.1534/genetics.104.038687. Epub 2005 Jan 16.
Integrated mapping in large-genome monocots has been carried out on a limited number of species. Furthermore, integrated maps are difficult to construct for these species due to, among other reasons, the specific plant populations needed. To fill these gaps, Alliums were chosen as target species and a new strategy for constructing suitable populations was developed. This strategy involves the use of trihybrid genotypes in which only one homeolog of a chromosome pair is recombinant due to interspecific recombination. We used genotypes from a trihybrid Allium cepa x (A. roylei x A. fistulosum) population. Recombinant chromosomes 5 and 8 from the interspecific parent were analyzed using genomic in situ hybridization visualization of recombination points and the physical positions of recombination were integrated into AFLP linkage maps of both chromosomes. The integrated maps showed that in Alliums recombination predominantly occurs in the proximal half of chromosome arms and that 57.9% of PstI/MseI markers are located in close proximity to the centromeric region, suggesting the presence of genes in this region. These findings are different from data obtained on cereals, where recombination rate and gene density tends to be higher in distal regions.
在大基因组单子叶植物中，仅对少数物种进行了整合图谱分析。此外，由于这些物种需要特定的植物群体等原因，构建整合图谱较为困难。为填补这些空白，选择葱属植物作为目标物种，并开发了一种构建合适群体的新策略。该策略涉及使用三杂交基因型，其中由于种间重组，染色体对中只有一个同源染色体是重组的。我们使用了三杂交洋葱（A. cepa）×（A. roylei×A. fistulosum）群体的基因型。利用基因组原位杂交对种间亲本的重组染色体5和8上的重组点进行可视化分析，并将重组的物理位置整合到这两条染色体的AFLP连锁图谱中。整合图谱显示，在葱属植物中，重组主要发生在染色体臂的近端一半，并且PstI/MseI标记的57.9%位于着丝粒区域附近，表明该区域存在基因。这些发现与在谷类作物上获得的数据不同，在谷类作物中，远端区域的重组率和基因密度往往更高。
