It would be helpful to have genomewide selection schemes that increase genetic gains within the same cost and same time as currently required in breeding programs. My objective was to assess if and how two-cycle genomewide selection can increase maize (Zea mays L.) genetic gains in a cost-neutral and time-neutral manner. As per industry sources, per-unit costs were assumed equal for genotyping, doubled haploidy, testcrossing, and phenotyping at one location. The values of genomewide prediction accuracy (r_MG) (0.20–0.80) and entry-mean heritability (0.60) mimicked those for maize yield. In simulations, two-cycle genomewide selection conducted as follows led to large gains: (a) genomewide selection among 200 to 240 Cycle 0 F₂ plants, (b) genomewide selection among 200 to 240 Cycle 1 doubled haploids, and (c) phenotyping of 35 to 45 doubled haploids at 12 locations. The largest gains from two-cycle genomewide selection were 124 to 178% of the largest gain from phenotypic selection and 112 to 135% of the largest gains (given the same r_MG) from one-cycle genomewide selection. When 8 to 10 Cycle 0 F₂ plants were intermated to form Cycle 1, the gains were numerically greater with two-cycle genomewide selection than with phenotypic selection at least 78% of the time. The best resource allocations for two-cycle genomewide selection were tantamount to substituting genomewide predictions for first-year phenotyping, thereby reducing the time required to release hybrid cultivars. The results indicated no reason for commercial maize breeders to rely solely on phenotypic selection during inbred development.

中文翻译：

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通过两轮全基因组选择升级玉米育种计划：相同的成本、相同或更少的时间和更大的收益

拥有全基因组选择计划将有助于在与育种计划当前所需的相同成本和相同时间内增加遗传收益。我的目标是评估双周期全基因组选择是否以及如何以成本中性和时间中性的方式增加玉米 ( Zea mays L.) 的遗传收益。根据行业来源，假设基因分型、双单倍体、测试杂交和一个地点的表型分析的单位成本相等。全基因组预测准确度 ( r _MG ) (0.20–0.80) 和进入平均遗传力 (0.60) 的值模拟了玉米产量的值。在模拟中，如下进行的两循环全基因组选择带来了巨大收益：(a) 200 到 240 循环 0 F ₂之间的全基因组选择植物，（b）在 200 到 240 个周期 1 双单倍体中的全基因组选择，以及（c）在 12 个位置对 35 到 45 个双单倍体进行表型分析。两循环全基因组选择的最大收益是表型选择最大收益的 124% 至 178%，以及单循环全基因组选择最大收益的 112% 至 135%（假定相同的r _MG）。当 8 到 10 周期 0 F ₂植物杂交形成周期 1，至少在 78% 的时间里，两周期全基因组选择的增益在数值上大于表型选择。两轮全基因组选择的最佳资源分配相当于用全基因组预测代替第一年表型，从而减少发布杂交品种所需的时间。结果表明商业玉米育种者没有理由在自交发展过程中仅仅依赖表型选择。