Department of Plant Science, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
Department of Forestry Engineering, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
PLoS One. 2019 Jul 25;14(7):e0220245. doi: 10.1371/journal.pone.0220245. eCollection 2019.
Cassava improvement using traditional breeding strategies is slow due to the species' long breeding cycle. However, the use of genomic selection can lead to a shorter breeding cycle. This study aimed to estimate genetic parameters for productive traits based on pedigree (pedigree and phenotypic information) and genomic (markers and phenotypic information) analyses using biparental crosses at different stages of selection. A total of 290 clones were genotyped and phenotyped for fresh root yield (FRY), dry matter content (DMC), dry yield (DY), fresh shoot yield (FSY) and harvest index (HI). The clones were evaluated in clonal evaluation trials (CET), preliminary yield trials (PYT), advanced yield trials (AYT) and uniform yield trials (UYT), from 2013 to 2018 in ten locations. The breeding stages were analyzed as follows: one stage (CET), two stages (CET and PYT), three stages (CET, PYT and AYT) and four stages (CET, PYT, AYT and UYT). The genomic predictions were analyzed via k-fold cross-validation based on the genomic best linear unbiased prediction (GBLUP) considering a model with genetic additive effects and genotype × location interactions. Genomic and pedigree accuracies were moderate to high (0.56-0.72 and 0.62-0.78, respectively) for important starch-related traits such as DY and FRY; when considering one breeding stage (CET) with the aim of early selection, the genomic accuracies ranged from 0.60 (DMC) to 0.71 (HI). Moreover, the correlations between the genomic estimation breeding values of one-stage genomic analysis and the estimated breeding values of the four-stage (full data set) pedigree analysis were high for all traits as well as for a selection index including all traits. The results indicate great possibilities for genomic selection in cassava, especially for selection early in the breeding cycle (saving time and effort).
利用传统的育种策略来改良木薯的速度较慢，因为该物种的繁殖周期较长。然而，利用基因组选择可以缩短繁殖周期。本研究旨在利用双亲杂交在不同选择阶段，基于系谱（系谱和表型信息）和基因组（标记和表型信息）分析，估计生产性状的遗传参数。共对 290 个无性系进行了基因型和表型分析，分析指标包括鲜薯产量（FRY）、干物质含量（DMC）、干产量（DY）、鲜薯产量（FSY）和收获指数（HI）。这些无性系在 2013 年至 2018 年的 10 个地点的无性系评价试验（CET）、初步产量试验（PYT）、高级产量试验（AYT）和均匀产量试验（UYT）中进行了评价。对不同的育种阶段进行了分析，分别为一个阶段（CET）、两个阶段（CET 和 PYT）、三个阶段（CET、PYT 和 AYT）和四个阶段（CET、PYT、AYT 和 UYT）。通过基于基因组最佳线性无偏预测（GBLUP）的 k 折交叉验证分析了基因组预测，考虑了包含遗传加性效应和基因型×地点互作的模型。对于重要的淀粉相关性状，如 DY 和 FRY，基因组和系谱的准确性中等偏高（0.56-0.72 和 0.62-0.78）；当考虑一个育种阶段（CET）以实现早期选择时，基因组的准确性范围为 0.60（DMC）至 0.71（HI）。此外，在所有性状以及包括所有性状的选择指数上，一阶段基因组分析的基因组估计育种值与四阶段（全数据集）系谱分析的估计育种值之间的相关性很高。结果表明，木薯基因组选择具有很大的可能性，特别是在育种周期早期（节省时间和精力）进行选择。
