Introgression of a quantitative trait locus (QTL) by successive backcrosses is used to improve elite lines (recurrent parent) by introducing alleles from exotic material (donor parent). In the absence of selection, the proportion of the donor genome decreases by half at each generation. However, since selection is for the donor allele at the QTL, elimination of the donor genome around that QTL will be much slower than in the rest of the genome (i.e. linkage drag). Using markers to monitor the genome around the QTL and in the genetic background can accelerate the return to the recurrent parent genome. Successful introgression of a locus depends partly on the occurrence of crossovers at favorable positions. However, the number of crossovers per generation is limited and their distribution along the genome is heterogeneous. Recently, techniques have been developed to modify these two recombination parameters. In this paper, we assess, by simulations in the context of Brassicaceae, the effect of increased recombination on the efficiency of introgression programs by studying the decrease in linkage drag and the recovery of the recurrent genome. The simulated selection schemes begin by two generations of foreground selection and continue with one or more generations of background selection. Our results show that, when the QTL is in a region that initially lacked crossovers, an increase in recombination rate can decrease linkage drag by nearly ten-fold after the foreground selection and improves the return to the recurrent parent. However, if the QTL is in a region that is already rich in crossovers, an increase in recombination rate is detrimental. Depending on the recombination rate in the region targeted for introgression, increasing it can be beneficial or detrimental. Thus, the simulations analysed in this paper help us understand how an increase in recombination rate can be beneficial. They also highlight the best methods that can be used to increase recombination rate, depending on the situation.

中文翻译：

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通过增加重组来增强回交计划

通过连续回交对定量性状基因座（QTL）进行渗入，通过引入来自外来物质（供体亲本）的等位基因来改善优良品系（亲本）。在没有选择的情况下，供体基因组的比例在每一代减少一半。但是，由于选择是针对QTL的供体等位基因，因此消除该QTL周围的供体基因组的速度将比其余基因组的消除速度慢得多（即连锁阻力）。使用标记物监测QTL周围和遗传背景中的基因组可以加速返回复发亲本基因组的过程。基因座的成功渗入部分取决于在有利位置发生交叉的情况。但是，每代的交换数量是有限的，并且它们在基因组上的分布是异质的。最近，已经开发了用于修饰这两个重组参数的技术。在本文中，我们通过在十字花科进行模拟，通过研究连锁阻力的减少和基因组的恢复来评估重组增加对基因渗入程序效率的影响。模拟的选择方案从两代前景选择开始，并以一代或多代背景选择继续。我们的结果表明，当QTL位于最初没有交叉的区域时，重组率的提高可以使前景选择后的连锁阻力降低近十倍，并提高返回亲本的回报。但是，如果QTL位于已经存在大量交叉点的区域中，则重组率的增加将是有害的。取决于渗入目标区域中的重组率，增加重组率可能是有益的，也可能是有害的。因此，本文分析的模拟有助于我们了解重组率的提高如何带来好处。它们还根据情况突出了可用于提高重组率的最佳方法。