Targeted recombination is the ability to induce or select for specific recombination points on chromosomes. A first study with the intermated B73 × Mo17 maize (Zea mays 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_Targeted) 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_Targeted ranged from around 60 to 400% among the populations, and targeted recombination did not increase gains in around 4% of the populations. The RE_Targeted 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.

中文翻译：

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从优良的双亲玉米种群中有针对性的重组预测的遗传增益。

靶向重组是诱导或选择染色体上特定重组点的能力。对B73×Mo17玉米（Zea mays L.）的种群进行的首次研究表明，靶向重组可使产量和其他农艺性状的预期收益翻倍。我们的目的是评估多种优良玉米种群中有针对性重组的定量性状的预期收获。从2000年到2008年，在美国的4至12个环境中对969个双亲玉米种群进行了表型分析。根据2911个单核苷酸多态性（SNP）位点的全基因组标记效应，确定了每个染色体一个和两个靶向重组的位置。相对效率（_针对RE计算）作为对靶标重组的预测应答除以对非靶标重组的预测应答。平均而言，靶向重组可使产量，水分和试验重量的预期遗传增益翻倍。对于每种性状，RE_目标人群的比例在60％至400％之间，目标重组不会增加4％人群的收益。再_有针对性随着父母之间相似度的增加而降低。在三个染色体上（针对产量和体重）的目标重组，对七个染色体（针对水分），与非目标重组相比，具有相同或更高的预测增益。靶向重组的标记间隔因人群和性状而异。总体而言，我们对多个优良玉米种群的研究结果表明，靶向重组是最有前途的育种方法。