Prospects for genomewide selection for quantitative traits in maize
Prospects for genomewide selection for quantitative traits in maize
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DOI：
10.2135/cropsci2006.11.0690
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发表时间：
2007-05-01
期刊：
影响因子：
2.3
通讯作者：
Yu, Jianming
中科院分区：
文献类型：
--
作者：
Bernardo, Rex;Yu, Jianming
利用廉价、丰富的分子标记技术研究玉米（Zea mays L.）允许育种者询问如何最好地使用分子标记来实现育种进展，而不需要对传统育种方法进行条件限制。全基因组选择是指基于标记的选择，而不首先鉴定具有显著效果的标记的子集。我们的目标是评估反应，由于全基因组选择与标记辅助复发选择（MARS）相比，并确定，在何种程度上可以最大限度地减少表型和基因分型全基因组选择。我们通过在第0周期评估加倍单倍体的测交性能来模拟全基因组选择，然后基于标记进行两个周期的选择。对个体进行N-m标记的基因分型，预测与每个Nm标记相关的育种值，并将其全部用于全基因组选择。我们发现，在不同数量的数量性状基因座（20，40和100）和遗传力水平，全基因组选择的反应是18%至43%，大于对MARS的反应。当在循环0中表型分型和基因分型的加倍单倍体的数目减少并且在循环1和2中基因分型的植物的数目增加时，维持对选择的响应。只有当每个标记数据点的成本降低到大约2美分时，这种最小化表型和最大化基因型的方案才是可行的。方便但不正确的假设相等的标记方差导致只有一个最小的损失的反应，全基因组选择。我们得出结论，全基因组选择，作为。这是一种利用廉价而丰富的分子标记的暴力黑箱程序，在玉米中上级MARS。
The availability of cheap and abundant molecular markers in maize (Zea mays L.) has allowed breeders to ask how molecular markers may best be used to achieve breeding progress, without conditioning the question on how breeding has traditionally been done. Genomewide selection refers to marker-based selection without first identifying a subset of markers with significant effects. Our objectives were to assess the response due to genomewide selection compared with marker-assisted-recurrent selection (MARS) and to determine, the extent to which phenotyping can be minimized and genotyping maximized in genomewide selection. We simulated genomewide selection by evaluating doubled haploids for testcross performance in Cycle 0, followed by two cycles of selection based on markers. Individuals were genotyped for N-m markers, and breeding values associated with each of the Nm markers were predicted and were all used in genomewide selection. We found that across different numbers of quantitative trait loci (20, 40, and 100) and levels of heritability, the response to genomewide selection was 18 to 43% larger than the response to MARS. Responses to selection were maintained when the number of doubled haploids phenotyped and genotyped in Cycle 0 was reduced and the number of plants genotyped in Cycles 1 and 2 was increased. Such schemes that minimize phenotyping and maximize genotyping would be feasible only if the cost per marker data point is reduced to about 2 cents. The convenient but incorrect assumption of equal marker variances led to only a minimal loss in the response,to genomewide selection. We conclude that genomewide selection, as. a brute-force and black-box procedure that exploits cheap and abundant molecular markers, is superior to MARS in maize.