INRA, UMR118 APBV, F-35653 Le Rheu Cedex, France.
New Phytol. 2010 Apr;186(1):102-12. doi: 10.1111/j.1469-8137.2010.03182.x. Epub 2010 Feb 8.
Polyploidy promotes the restructuring of merged genomes within initial generations of resynthesized Brassica napus, possibly caused by homoeologous recombination at meiosis. However, little is known about the impact of the first confrontation of two genomes at the first meiosis which could lead to genome exchanges in progeny. Here, we assessed the role of the first meiosis in the genome instability of synthetic B. napus. We used three different newly resynthesized B. napus plants and established meiotic pairing frequencies for the A and C genomes. We genotyped the three corresponding progenies in a cross to a natural B. napus on the two homoeologous A1 and C1 chromosomes. Pairing at meiosis in a set of progenies with various rearrangements was scored. Here, we confirmed that the very first meiosis of resynthesized plants of B. napus acts as a genome blender, with many of the meiotic-driven genetic changes transmitted to the progenies, in proportions that depend significantly on the cytoplasm background inherited from the progenitors. We conclude that the first meiosis generates rearrangements on both genomes and promotes subsequent restructuring in further generations. Our study advances the knowledge on the timing of genetic changes and the mechanisms that may bias their transmission.
多倍体在油菜的合成初期通过减数分裂的同源重组促进了合并基因组的重排，然而，对于两个基因组在第一次减数分裂中首次接触导致后代发生基因组交换的影响知之甚少。在这里，我们评估了第一次减数分裂在合成油菜基因组不稳定性中的作用。我们使用了三种不同的新合成油菜植物，并建立了 A 组和 C 组基因组的减数分裂配对频率。我们对与天然油菜杂交的三个相应后代在两条同源 A1 和 C1 染色体上进行了基因分型。在一组具有各种重排的后代中对减数分裂的配对进行了评分。在这里，我们证实了油菜合成植物的第一次减数分裂充当了基因组搅拌机，许多减数分裂驱动的遗传变化以显著依赖于从亲本继承的细胞质背景的比例传递给后代。我们得出结论，第一次减数分裂在两个基因组上产生重排，并促进了进一步后代的后续重排。我们的研究推进了对遗传变化发生时间及其可能偏向其传递的机制的认识。
