Kopecký D, Havránková M, Loureiro J, Castro S, Lukaszewski A J, Bartos J, Kopecká J, Dolezel J
Laboratory of Molecular Cytogenetics and Cytometry, Institute of Experimental Botany, Olomouc, Czech Republic.
Cytogenet Genome Res. 2010 Jul;129(1-3):162-72. doi: 10.1159/000313379. Epub 2010 May 26.
Crossing over-based recombination is a powerful tool for generating new allelic combinations during sexual reproduction. It usually occurs between homologous chromosomes. However, under some conditions, homoeologues may also be capable of crossing over. Whether homologous and homoeologous crossovers are equivalent and governed by the same rules has never been established. Here we report on chromosome distribution of homoeologous crossovers in a unique system of Festuca x Lolium hybrids. Unlike in most other hybrids, in these intergeneric hybrids, homoeologous chromosomes are capable of pairing and crossing over with frequencies approaching that of homologues. At the same time, genome divergence makes cytological detection of chromosome recombination feasible. We analyzed the distribution of homoeologous recombination along individual chromosomes in a complete set of intergeneric single chromosome substitutions from F. pratensis into tetraploid L. multiflorum. Homoeologous recombination sites were not evenly distributed along the chromosomes, being concentrated in intercalary regions of the arms and reduced in proximal and distal regions. Several recombination hotspots and cold spots were found along individual chromosomes and the recombination was not affected by the presence of a secondary constriction. Our results indicate that despite the uneven distribution of homoeologous recombination, introgression of any part of the F. pratensis genome into L. multiflorum is feasible.
基于交换的重组是有性生殖过程中产生新等位基因组合的有力工具。它通常发生在同源染色体之间。然而，在某些条件下，部分同源染色体也可能发生交换。同源和部分同源交换是否等效且受相同规则支配，这一点尚未得到证实。在此，我们报道了羊茅属与黑麦草属杂交种这一独特系统中部分同源交换的染色体分布情况。与大多数其他杂交种不同，在这些属间杂交种中，部分同源染色体能够配对并发生交换，其频率接近同源染色体的交换频率。同时，基因组差异使得对染色体重组进行细胞学检测成为可能。我们分析了从草地羊茅导入四倍体多花黑麦草的一套完整的属间单染色体代换系中，部分同源重组在各个染色体上的分布情况。部分同源重组位点在染色体上分布不均，集中在染色体臂的居间区域，而在近端和远端区域减少。沿着各个染色体发现了几个重组热点和冷点，并且重组不受次缢痕存在的影响。我们的结果表明，尽管部分同源重组分布不均，但将草地羊茅基因组的任何部分导入多花黑麦草都是可行的。
