Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843, USA.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
G3 (Bethesda). 2021 Jun 17;11(6). doi: 10.1093/g3journal/jkab075.
Plant height (PHT) in maize (Zea mays L.) has been scrutinized genetically and phenotypically due to relationship with other agronomically valuable traits (e.g., yield). Heritable variation of PHT is determined by many discovered quantitative trait loci; however, phenotypic effects of such loci often lack validation across environments and genetic backgrounds, especially in the hybrid state grown by farmers rather than the inbred state more often used by geneticists. A previous genome-wide association study using a topcrossed hybrid diversity panel identified two novel quantitative trait variants controlling both PHT and grain yield. Here, heterogeneous inbred families demonstrated that these two loci, characterized by two single nucleotide polymorphisms (SNPs), cause phenotypic variation in inbred lines, but that size of these effects were variable across four different genetic backgrounds, ranging from 1 to 10 cm. Weekly unoccupied aerial system flights demonstrated the two SNPs had larger effects, varying from 10 to 25 cm, in early growth while effects decreased toward the end of the season. These results show that allelic effect sizes of economically valuable loci are both dynamic in temporal growth and dynamic across genetic backgrounds, resulting in informative phenotypic variability overlooked following traditional phenotyping methods. Public genotyping data show recent favorable allele selection in elite temperate germplasm with little change across tropical backgrounds. As these loci remain rarer in tropical germplasm, with effects most visible early in growth, they are useful for breeding and selection to expand the genetic basis of maize.
由于与其他具有农艺价值的性状（例如产量）有关，玉米（Zea mays L.）的株高（PHT）一直受到遗传和表型上的关注。PHT 的可遗传性变异由许多已发现的数量性状基因座决定；然而，这些基因座的表型效应往往缺乏在不同环境和遗传背景下的验证，尤其是在农民种植的杂交状态下，而不是遗传学家更常使用的自交状态下。之前使用杂交多样性面板进行的全基因组关联研究鉴定出了两个控制 PHT 和籽粒产量的新的数量性状变异。在这里，异质自交系群体表明，这两个由两个单核苷酸多态性（SNP）特征的基因座导致了自交系的表型变异，但这些效应的大小在四个不同的遗传背景下有所不同，范围从 1 到 10 厘米。每周使用无人空中系统飞行表明，这两个 SNP 在早期生长中具有更大的影响，从 10 到 25 厘米不等，而在季节结束时影响会减小。这些结果表明，经济价值基因座的等位基因效应大小在时间生长中是动态的，并且在遗传背景中也是动态的，这导致了传统表型方法忽略的信息表型可变性。公共基因分型数据显示，在温带种质中，有利等位基因的选择最近有所增加，而在热带背景下几乎没有变化。由于这些基因座在热带种质中仍然较为罕见，并且在生长早期最为明显，因此它们对于扩大玉米的遗传基础具有有用的选择和选育作用。
