导读

柳枝稷适应性强，产量潜力大，且对环境友好，是重要的能源作物。柳枝稷建植过程中死亡率高达90%。选择合适的柳枝稷生态型可以减少其建植过程中的死亡率。之前有关柳枝稷短期和长期建植过程中草种的选择，多依赖草的形态学和生理指标，即使采用基因组数据结果也是模棱两可。但是，柳枝稷高度的自然选择进程依靠育种群体中的遗传变异，建立合适的建植选择机制可能将成为非常重要的育种工具。建植选择对草种质适应特殊的地理环境和栽培环境也非常重要。

威斯康星大学的Neal W. Tilhou 团队对杂交和低地2个育种群体的46个半同胞家系柳枝稷在建植前和3年建植过程取样进行混池DNA测序分析。最终，一共306个DNA混池中鉴定到382 388个双等位基因单核苷酸多态性(SNP)标记。其中等位基因频率通过固定系数Fst=s2/[p(p-1)+s2/r]指示。建植前和3年建植过程中对抽穗期和冬季存活率2个性状进行检测并建立表型数据库。基于FLOMAS，预测柳枝稷建植进程中的苗存活率，并成功预测出建植进程中高存活率草单株主要来源杂交群体。本研究通过简单的混池测序DNA数据建立的数学模型，可为准确选择柳枝稷草地建植选择存活率高的草种提供重要参考。相对于传统表型选择，本研究建立的方法更准确，这为高效节本建植柳枝稷草地具有重要意义。

图表

Table 1: The sampling effort and germplasm history for 46 half-sib families

Note: Families from the same germplasm source were collected from a common and isolated cross-pollination block. Samples indicate the number of DNA pools sequenced for each stage. Unequal sample numbers are due to the unbalanced experimental design and reduced sampling effort during Year 3.

Table 2: Candidate smoothing spline-defined windows for selection during sward establishment based on their occurrence as outliers in a minimum of three half-sib families based on the W-statistic

Note: Reported window positions are the narrowest band of markers which maximize the number of overlapping windows. Window Fst, W-statistics, and read depths are the mean values for all significant families within overlapping windows.

Figure 1: Reference allele frequencies of single-SNP outlier windows in DNA pools collected from half-sib families in a greenhouse (GH) and in the first year, the second year, or the third year of sward establishment. Families are derived from either the Liberty cultivar (a), or diverse Lowland populations (b). Each gray line indicates a family and includes all 26 families used in the analysis (18 within Liberty and 8 within Lowland). Black lines indicate the mean allele frequency of all families within the breeding population.

Figure 2: Predicted changes in genomically estimated breeding values (ΔGEBVs) during establishment in switchgrass seeded swards. (a) and (b) GEBVs of winter survivorship scores. (c) and (d) GEBVs of heading dates. Line colors indicate the initial (GH) GEBVs for each family, while the line trajectories indicate the change in GEBV over the course of sward establishment. GEBV, genomically estimated breeding value.

Figure 3: Principal components generated from marker data (m = 35 478) from the FLOMAS switchgrass trial containing four breeding groups. Point colors indicate genomically estimated breeding values for establishment survival based on training data from the hybrid breeding group. Units for sward survival were arbitrarily assigned scores (greenhouse samples = 0, Year 1 sward samples = 1, Year 2 sward samples = 2, Year 3 sward samples = 3).

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文章信息

原文链接：https://onlinelibrary.wiley.com/doi/10.1002/glr2.12007

内容来源：Grassland Research（草地研究）第1卷第1期（投稿：2022-02-20；接收：2022-03-23；刊发：2022-04-30）

DOI： https://doi.org/10.1002/glr2.12007

引用格式：Tilhou, N. W., Kaeppler, S.M., & Casler, M. D. (2022). Strong parallelevidence of selection during switchgrass swardestablishment in hybrid and lowland ecotypes.Grassland Research,1(1), 31–42.

编译者：胡涛 兰州大学草地农业科技学院 教授

说明：该文仅代表编译者对论文的理解，如需参考和引用相关内容，请查阅原文。

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