Institute of Crop Science/CIMMYT-China, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
National Maize Improvement Center, China Agricultural University, Beijing, 100094, China.
J Appl Genet. 2021 Sep;62(3):405-418. doi: 10.1007/s13353-021-00629-0. Epub 2021 Mar 31.
Waterlogging has increasingly become one of the major constraints to maize (Zea mays L.) production in some maize growing areas as it seriously decreases the yield. Waterlogging tolerance in maize germplasm provides a basis for maize waterlogging improvement. In this study, nine seedling traits, plant height (PH), root length (RL), shoot dry weight (SDW), root dry weight (RDW), adventitious root number (ARN), node number of brace root (BRNN), brace root number (BRN), brace root dry weigh (BRDW), survival rate (SR), and the secondary traits that were defined as relative phenotypic value of seedling traits under waterlogging and control treatments were used in a natural population that contain 365 inbred lines to evaluate the waterlogging tolerance of tropical maize. The result showed that maize waterlogging tolerance was genetically controlled and seedling traits were significantly different between the control and waterlogging treatments. PH, RL, SDW, and RDW are important seedling traits for waterlogging tolerance identification. Some tropical maize inbred lines were identified with extreme waterlogging tolerance that can provide an important germplasm resource for breeding. Population structure analysis showed that two major phylogenetic subgroups in tropical maize could be identified. Genome-wide association study (GWAS) using 39,266 single nucleotide polymorphisms (SNPs) across the whole genome identified 49 trait-SNPs distributed on over all 10 chromosomes excluding chromosome 10. Seventy-one significant SNPs, distributed on all 10 chromosomes excluding chromosome 5, were identified by extend bulked sample analysis (Ext-BSA) based on the inbred lines with extreme phenotypes. GWAS and Ext-BSA identified the same loci on bin1.07, bin6.01, bin2.09, bin6.04, bin7.02, and bin7.03. Nine genes were proposed as potential candidate genes. Cloning and functional validation of these genes would be helpful for understanding the molecular mechanism of waterlogging tolerance in maize.
涝渍已成为一些玉米种植区玉米生产的主要限制因素之一，因为它严重降低了产量。玉米种质资源的耐涝性为玉米耐涝性改良提供了基础。本研究利用自然群体中的 365 个自交系，采用 9 个幼苗性状（株高（PH）、根长（RL）、地上部干重（SDW）、根干重（RDW）、不定根数（ARN）、支撑根节数（BRNN）、支撑根数（BRN）、支撑根干重（BRDW）、存活率（SR）和次生性状），定义为幼苗在涝渍和对照处理下的相对表型值，对热带玉米的耐涝性进行评价。结果表明，玉米耐涝性受遗传控制，幼苗性状在对照和涝渍处理之间存在显著差异。PH、RL、SDW 和 RDW 是鉴定耐涝性的重要幼苗性状。一些热带玉米自交系表现出极端耐涝性，可以为育种提供重要的种质资源。群体结构分析表明，热带玉米可分为两个主要的系统发育亚群。利用全基因组 39266 个单核苷酸多态性（SNP）进行全基因组关联研究（GWAS），在除第 10 号染色体外的所有 10 条染色体上鉴定到 49 个与性状相关的 SNP。基于极端表型的自交系，通过扩展的 bulked sample analysis（Ext-BSA）鉴定到 71 个显著 SNP，分布在除第 5 号染色体外的所有 10 条染色体上。GWAS 和 Ext-BSA 都在 bin1.07、bin6.01、bin2.09、bin6.04、bin7.02 和 bin7.03 上鉴定到相同的位点。提出了 9 个基因作为潜在的候选基因。这些基因的克隆和功能验证将有助于理解玉米耐涝性的分子机制。
