UMR 0320, Quantitative Genetics and Evolution (GQE) - Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91190, Gif-Sur-Yvette, France.
Bayer Crop Science NV, Technologiepark 38, 9052, Ghent, Belgium.
Theor Appl Genet. 2019 May;132(5):1523-1542. doi: 10.1007/s00122-019-03296-2. Epub 2019 Feb 7.
Silage quality traits of maize hybrids between the Dent and Flint heterotic groups mostly involved QTL specific of each parental group, some of them showing unfavorable pleiotropic effects on yield. Maize (Zea mays L.) is commonly used as silage for cattle feeding in Northern Europe. In addition to biomass production, improving whole-plant digestibility is a major breeding objective. To identify loci involved in the general (GCA, parental values) and specific combining ability (SCA, cross-specific value) components of hybrid value, we analyzed an incomplete factorial design of 951 hybrids obtained by crossing inbred lines issued from two multiparental connected populations, each specific to one of the heterotic groups used for silage in Europe ("Dent" and "Flint"). Inbred lines were genotyped for approximately 20K single nucleotide polymorphisms, and hybrids were phenotyped in eight environments for seven silage quality traits measured by near-infrared spectroscopy, biomass yield and precocity (partly analyzed in a previous study). We estimated variance components for GCA and SCA and their interaction with environment. We performed QTL detection using different models adapted to this hybrid population. Strong family effects and a predominance of GCA components compared to SCA were found for all traits. In total, 230 QTL were detected, with only two showing SCA effects significant at the whole-genome level. More than 80% of GCA QTL were specific of one heterotic group. QTL explained individually less than 5% of the phenotypic variance. QTL co-localizations and correlation between QTL effects of quality and productivity traits suggest at least partial pleiotropic effects. This work opens new prospects for improving maize hybrid performances for both biomass productivity and quality accounting for complementarities between heterotic groups.
青贮玉米杂交种的青贮质量特性主要涉及每个亲本组特有的 QTL，其中一些 QTL 对产量表现出不利的多效性影响。玉米（Zea mays L.）通常被用作北欧牛饲料的青贮料。除了生物量生产外，提高整株植物的消化率是主要的育种目标。为了鉴定参与杂种值的一般配合力（GCA，亲本值）和特殊配合力（SCA，交叉特异性值）成分的基因座，我们分析了由来自两个多亲系连接群体的自交系杂交获得的不完全因子设计的 951 个杂交种，每个群体都与欧洲青贮用的一个杂种组（“Dent”和“Flint”）有关。自交系被大约 20K 个单核苷酸多态性进行了基因型分析，杂交种在 8 个环境中进行了青贮质量特性（通过近红外光谱测量，生物量产量和早熟性）的表型分析（部分在前一项研究中进行了分析）。我们估计了 GCA 和 SCA 及其与环境的互作的方差分量。我们使用适应于这种杂交群体的不同模型进行了 QTL 检测。所有性状均发现强家系效应和 GCA 成分比 SCA 成分占主导地位。总共检测到 230 个 QTL，只有两个显示出全基因组水平上显著的 SCA 效应。超过 80%的 GCA QTL 是特定于一个杂种组的。单个 QTL 解释的表型方差小于 5%。质量和生产力性状的 QTL 共定位和 QTL 效应之间的相关性表明至少存在部分的多效性效应。这项工作为提高玉米杂种在生物量生产力和质量方面的表现开辟了新的前景，同时考虑了杂种组之间的互补性。
