David J L, Boudec P, Gallais A
INRA-UPS, Ferme du Moulon, Gif sur Yvette, France.
Genetics. 1995 Apr;139(4):1797-803. doi: 10.1093/genetics/139.4.1797.
A model is proposed to describe the genetic value of 4x-2x hybrids resulting from crosses between tetraploid genitors and diploid genitors that produce 2n gametes. The model takes into account the genetic consequences of the First Division Restitution (FDR) and Second Division Restitution (SDR) meiosis, particularly on the homozygosity level that 2n gametes contribute to 4x-2x hybrids. As genes can be identical by descent, numerous parameters are needed in the classical approach to describe the inbreeding effects on the mean and variance of 4x-2x hybrids. Using the concept of test value, the model allows a large decrease in the number of required parameters. The model gives the components of genetic variance and usual covariances between relatives using these synthetic parameters. The model is then used to study the efficiency of a recurrent breeding scheme to improve diploid genitors for their combining ability with tetraploid genitors. It appears that, in presence of dominance, ignoring the meiosis pattern will lead to an overestimation of additive variance and then of genetic advance. Some genetic considerations on the differences between FDR and SDR mechanisms lead us to suggest an experimental comparison of their respective advantages and disadvantages for the type of considered recurrent selection. An experimental crossing design is proposed to obtain estimates of the genetic parameters needed for this comparison.
提出了一个模型来描述四倍体亲本与产生2n配子的二倍体亲本杂交产生的4x - 2x杂种的遗传值。该模型考虑了第一次分裂重组（FDR）和第二次分裂重组（SDR）减数分裂的遗传后果，特别是2n配子对4x - 2x杂种纯合性水平的影响。由于基因可能是同源相同的，在经典方法中需要大量参数来描述近亲繁殖对4x - 2x杂种均值和方差的影响。利用测试值的概念，该模型可以大幅减少所需参数的数量。该模型使用这些综合参数给出了遗传方差的组成部分以及亲属之间常见的协方差。然后，该模型用于研究轮回育种方案提高二倍体亲本与四倍体亲本配合力的效率。结果表明，在存在显性的情况下，忽略减数分裂模式会导致对加性方差进而对遗传进展的高估。对FDR和SDR机制差异的一些遗传学考虑使我们建议对它们在考虑的轮回选择类型中的各自优缺点进行实验比较。提出了一种实验杂交设计，以获得这种比较所需的遗传参数估计值。
