National Maize Improvement Center, Beijing Key Laboratory of Crop Genetic Improvement, Laboratory of Crop Heterosis and Utilization, Joint International Research Laboratory of Crop Molecular Breeding, China Agricultural University, No.2 Yuanmingyuan West Rd, Haidian District, Beijing, 100193, China.
Department of Agronomy, Iowa State University, 513 Farm House Ln, Ames, IA, 50011-1050, USA.
Plant J. 2018 Mar;93(6):1032-1044. doi: 10.1111/tpj.13828. Epub 2018 Feb 23.
The maize nodal root system plays a crucial role in the development of the aboveground plant and determines the yield via the uptake of water and nutrients in the field. However, the genetic architecture of the maize nodal root system is not well understood, and it has become the 'dark matter' of maize genetics. Here, a large teosinte-maize population was analyzed, and high-resolution mapping revealed that 62 out of 133 quantitative trait loci (QTLs), accounting for approximately half of the total genetic variation in nodal root number, were derived from QTLs for flowering time, which was further validated through a transgenic analysis and a genome-wide association study. However, only 16% of the total genetic variation in nodal root number was derived from QTLs for plant height. These results gave a hint that flowering time played a key role in shaping nodal root number via indirect selection during maize domestication. Our results also supported that more aerial nodal roots and fewer crown roots might be favored in temperate maize, and this root architecture might efficiently improve root-lodging resistance and the ability to take up deep water and nitrogen under dense planting.
玉米节根系统在地上植物的发育中起着至关重要的作用，并通过在田间吸收水和养分来决定产量。然而，玉米节根系统的遗传结构还不是很清楚，它已经成为玉米遗传学的“暗物质”。在这里，分析了一个大型的玉米-类蜀黍群体，高分辨率图谱表明，在 133 个数量性状位点（QTL）中有 62 个（约占节点根数量总遗传变异的一半）来自开花时间的 QTL，这通过转基因分析和全基因组关联研究得到了进一步验证。然而，节点根数量的总遗传变异只有 16%来自株高的 QTL。这些结果表明，在玉米驯化过程中，开花时间通过间接选择在塑造节点根数量方面发挥了关键作用。我们的研究结果还表明，温带玉米可能更喜欢更多的气生根和更少的冠根，这种根系结构可能有效地提高根倒伏阻力和在密植条件下吸收深层水和氮的能力。
