Key Laboratory of Protein Chemistry and Fish Developmental Biology of Education Ministry of China, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
Sci Rep. 2016 Oct 5;6:34417. doi: 10.1038/srep34417.
To better understand genomic changes in the early generations after polyploidisation, we examined the chromosomal consequences of genomic merger in allotetraploid hybrids (4 nF) (AABB, 4n = 148) of Carassius auratus red var. (RCC) (AA, 2n = 100) (♀) × Megalobrama amblycephala (BSB) (BB, 2n = 48) (♂). Complete loss of the paternal 5S rDNA sequence and the expected number of maternal chromosomal loci were found in 4 nF, suggesting directional genomic changes occurred in the first generations after polyploidisation. Recent studies have reported instability of newly established allotetraploid genomes. To assess this in the newly formed 4 nF genome, we performed fluorescence in situ hybridisation on an allotetraploid gynogenetic hybrid (4 nG) (AABB, 4n = 148) and an allopentaploid hybrid (5 nH) (AABBB, 5n = 172) from 4 nF (♀) × BSB (♂) with 5S rDNA gene and centromere probes from RCC, the original diploid parent. The expected numbers of maternal chromosomal loci were found in 4 nG, while chromosomal locus deletions and chromosome recombinations were detected in 5 nH. These observations suggest that abnormal meiosis did not lead to obvious genomic changes in the newly established allotetraploid genomes, but hybridisation with the original diploid parent resulted in obvious genomic changes in the newly established allotetraploid genomes, as was found for the maternal genome.
为了更好地理解多倍体化后早期世代的基因组变化，我们研究了 Carassius auratus red var.（RCC）（AA，2n=100）（♀）×Megalobrama amblycephala（BSB）（BB，2n=48）（♂）异源四倍体杂种（4nF）（AABB，4n=148）中基因组融合的染色体后果。在 4nF 中发现了父本 5S rDNA 序列的完全丢失和预期数目的母本染色体位点，这表明在多倍体化后的第一代发生了定向的基因组变化。最近的研究报道了新建立的异源四倍体基因组的不稳定性。为了评估在新形成的 4nF 基因组中这种情况，我们用来自 RCC 的 5S rDNA 基因和着丝粒探针对由 4nF（♀）×BSB（♂）产生的异源雌核发育四倍体杂种（4nG）（AABB，4n=148）和异源五倍体杂种（5nH）（AABBB，5n=172）进行了荧光原位杂交。在 4nG 中发现了预期数目的母本染色体位点，而在 5nH 中检测到了染色体位点缺失和染色体重组。这些观察结果表明，异常减数分裂并没有导致新建立的异源四倍体基因组发生明显的基因组变化，但与原始二倍体亲本的杂交导致了新建立的异源四倍体基因组发生了明显的基因组变化，就像母本基因组一样。
