Plant Genome. 2019 Mar;12(1). doi: 10.3835/plantgenome2018.08.0062.
Targeted recombination is the ability to induce or select for specific recombination points on chromosomes. A first study with the intermated B73 × Mo17 maize ( L.) population showed that targeted recombination doubles the predicted gains for yield and other agronomic traits. Our objective was to assess the predicted gains from targeted recombination for quantitative traits in multiple, elite maize populations. A total of 969 biparental maize populations were phenotyped at four to 12 environments in the United States from 2000 to 2008. Positions of one and two targeted recombinations per chromosome were determined from genomewide marker effects for 2911 single nucleotide polymorphism (SNP) loci. Relative efficiency (RE) was calculated as the predicted response to targeted recombination divided by the predicted response to nontargeted recombination. On average, targeted recombination doubled the predicted genetic gains for yield, moisture, and test weight. For each trait, RE ranged from around 60 to 400% among the populations, and targeted recombination did not increase gains in around 4% of the populations. The RE tended to decrease as the similarity between the parents increased. Having targeted recombination on three chromosomes (for yield and test weight) to seven chromosomes (for moisture) led to the same or greater predicted gain than nontargeted recombination. Marker intervals for targeted recombination varied across populations and traits. Overall, our results for multiple, elite maize populations indicated that targeted recombination is a most promising breeding approach.
靶向重组是诱导或选择染色体上特定重组点的能力。第一项使用互交 B73×Mo17 玉米（L.）群体的研究表明，靶向重组使产量和其他农艺性状的预期增益增加了一倍。我们的目标是评估多个优良玉米群体中靶向重组对数量性状的预期增益。从 2000 年到 2008 年，在美国的 4 到 12 个环境中对总共 969 个双亲玉米群体进行了表型分析。通过对 2911 个单核苷酸多态性（SNP）位点的全基因组标记效应确定了每个染色体上一个和两个靶向重组的位置。相对效率（RE）的计算方法是将靶向重组的预测响应除以非靶向重组的预测响应。平均而言，靶向重组使产量、水分和测试重量的预期遗传增益增加了一倍。对于每种性状，RE 在群体之间的范围从 60%到 400%不等，并且大约 4%的群体中靶向重组没有增加增益。RE 往往随着亲本之间的相似性增加而降低。在三个染色体（产量和测试重量）上进行靶向重组，在七个染色体（水分）上进行靶向重组，其预测增益与非靶向重组相同或更大。靶向重组的标记区间因群体和性状而异。总的来说，我们对多个优良玉米群体的研究结果表明，靶向重组是一种最有前途的育种方法。
