Genomic selection (GS) can substantially reduce breeding cycle times in forest trees compared to traditional breeding cycles. Practical implementation of GS in tree breeding requires an assessment of significant drivers of genetic gains over time, which may differ among species and breeding objectives. We present results of a GS study of growth and wood quality traits in an operational Eucalyptus grandis breeding program in South Africa. The training population consisted of 1575 full and half-sib individuals, genotyped with the Eucalyptus (EUChip60K) SNP chip resulting in 15,040 informative SNP markers. The accuracy of the GS models ranged from 0.47 (diameter) to 0.67 (fibre width). We compared a 4-year GS breeding cycle equivalent to half of a traditional 8-year E. grandis breeding cycle and obtained GS efficiencies ranging from 1.20 (wood density) to 1.62 (fibre length). Simulated over 17 years, the ratio of the accumulated genetic gains between three GS cycles and two traditional breeding cycles ranged from 1.53 (diameter) to 3.35 (wood density). To realise these genetic gains per unit time in E. grandis breeding, we show that significant adjustments have to be made to integrate GS into operational breeding steps.

与传统的繁殖周期相比，基因组选择（GS）可以大大减少林木的繁殖周期。GS在树木育种中的实际实施需要评估随时间推移遗传增益的重要驱动因素，这在物种和育种目标之间可能有所不同。我们介绍了在南非开展的桉树繁殖计划中的生长和木材品质性状的GS研究结果。训练人群由1575名同胞和半同胞个体组成，他们用桉树（EUChip60K）SNP芯片进行了基因分型，产生了15,040个信息丰富的SNP标记。GS型号的精度范围从0.47（直径）到0.67（纤维宽度）。我们比较了一个4年的GS繁殖周期，相当于一个传统的8年的大肠埃希斯犬繁殖周期的一半，得出的GS效率从1.20（木材密度）到1.62（纤维长度）不等。经过17年的模拟，三个GS周期与两个传统育种周期之间累积的遗传增益之比为1.53（直径）至3.35（木材密度）。为了在大肠埃希氏菌育种中实现每单位时间的这些遗传增益，我们表明必须进行重大调整才能将GS整合到可操作的育种步骤中。