Xu Guanghui, Wang Xufeng, Huang Cheng, Xu Dingyi, Li Dan, Tian Jinge, Chen Qiuyue, Wang Chenglong, Liang Yameng, Wu Yaoyao, Yang Xiaohong, Tian Feng
National Maize Improvement Center, China Agricultural University, Beijing, 100193, China.
New Phytol. 2017 Apr;214(2):852-864. doi: 10.1111/nph.14400. Epub 2017 Jan 9.
Maize (Zea mays) tassels underwent profound morphological changes during maize domestication and improvement. Although a number of genes affecting maize inflorescence development have been identified, the genetic basis of the morphological changes in maize tassels since domestication is not well understood. Here, using a large population of 866 maize-teosinte BC S recombinant inbred lines genotyped using 19 838 single nucleotide polymorphism (SNP) markers, we performed high-resolution quantitative trait locus (QTL) mapping for five tassel morphological traits. We showed that the five tassel traits were associated with different genetic architecture features. Known genes for maize inflorescence development identified by mutagenesis were significantly enriched in the tassel trait QTLs, and many of these genes, including ramosa1 (ra1), barren inflorescence2 (bif2), unbranched2 (ub2), zea floricaula leafy2 (zfl2) and barren stalk fastigiate1 (baf1), showed evidence of selection. An in-depth nucleotide diversity analysis at the bif2 locus identified strong selection signatures in the 5'-regulatory region. We also found that several known flowering time genes co-localized with tassel trait QTLs. A further association analysis indicated that the maize photoperiod gene ZmCCT was significantly associated with tassel size variation. Using near-isogenic lines, we narrowed down a major-effect QTL for tassel length, qTL9-1, to a 513-kb physical region. These results provide important insights into the genetic architecture that controls maize tassel evolution.
玉米（Zea mays）雄穗在玉米驯化和改良过程中经历了深刻的形态变化。尽管已经鉴定出许多影响玉米花序发育的基因，但对于驯化以来玉米雄穗形态变化的遗传基础仍知之甚少。在此，我们利用866个玉米-大刍草BC5S重组自交系组成的大群体，通过19838个单核苷酸多态性（SNP）标记进行基因分型，对五个雄穗形态性状进行了高分辨率数量性状位点（QTL）定位。我们发现这五个雄穗性状与不同的遗传结构特征相关。通过诱变鉴定出的玉米花序发育已知基因在雄穗性状QTL中显著富集，其中许多基因，包括分枝1（ramosa1，ra1）、无花序2（barren inflorescence2，bif2）、不分枝2（unbranched2，ub2）、玉米花椰菜叶状2（zea floricaula leafy2，zfl2）和光秃茎紧凑1（barren stalk fastigiate1，baf1），都显示出选择的证据。对bif2位点的深入核苷酸多样性分析在其5'调控区域鉴定出强烈的选择信号。我们还发现几个已知的开花时间基因与雄穗性状QTL共定位。进一步的关联分析表明，玉米光周期基因ZmCCT与雄穗大小变异显著相关。利用近等基因系，我们将一个控制雄穗长度的主效QTL，qTL9-1，定位到一个513 kb的物理区域。这些结果为控制玉米雄穗进化的遗传结构提供了重要见解。
