Kernel size is an important agronomic trait for grain yield in maize. The purpose of this study is to map QTLs and predict candidate genes for kernel size in maize. A total of 199 F2 and its F2:3 lines from the cross between SG5/SG7 were developed. A composite interval mapping (CIM) method was used to detect QTLs in three environments of F2 and F2:3 populations. The result showed that a total of 10 QTLs for kernel size were detected, among which were five QTLs for kernel length (KL) and five QTLs for kernel width (KW). Two stable QTLs, qKW-1, and qKL-2, were mapped in all three environments. Three QTLs, qKL-1, qKW-1, and qKW-2, were overlapped with the QTLs identified from previous studies. In order to validate and fine map qKL-2, near-isogenic lines (NILs) were developed by continuous backcrossing between SG5 as the donor parent and SG7 as the recurrent parent. Marker-assisted selection was conducted from BC2F1 generation with molecular markers near qKL-2. A secondary linkage map with six markers around the qKL-2 region was developed and used for fine mapping of qKL-2. Finally, qKL-2 was confirmed in a 1.95 Mb physical interval with selected overlapping recombinant chromosomes on maize chromosome 9 by blasting with the Zea_Mays_B73 v4 genome. Transcriptome analysis showed that a total of 11 out of 40 protein-coding genes differently expressed between the two parents were detected in the identified qKL-2 interval. GRMZM2G006080 encoding a receptor-like protein kinase FERONIA, was predicted as a candidate gene to control kernel size. The work will not only help to understand the genetic mechanisms of kernel size of maize but also lay a foundation for further fine mapping and even cloning of the promising loci.
中文翻译:
玉米 (Zea mays) 赋予籽粒大小的主要 QTL 的 QTL 分析和精细定位
籽粒大小是玉米籽粒产量的重要农艺性状。本研究的目的是绘制 QTL 图谱并预测玉米籽粒大小的候选基因。来自SG5/SG7之间杂交的总共199个F 2及其F 2 : 3品系被开发出来。采用复合区间作图(CIM)方法检测F 2和F 2 : 3群体三种环境中的QTL。结果表明,共检测到10个与籽粒大小相关的QTL,其中5个与籽粒长度(KL)相关的QTL,5个与籽粒宽度(KW)相关的QTL。两个稳定的QTL,qKW-1, 和qKL-2,在所有三个环境中进行了映射。三个QTL,qKL-1, qKW-1, 和qKW-2,与之前研究中确定的 QTL 重叠。为了验证和精细地图qKL-2,近等基因系(NIL)是通过 SG5 作为供体亲本和 SG7 作为轮回亲本之间的连续回交而开发的。从 BC 2 F 1代开始进行标记辅助选择,分子标记接近qKL-2。二级连锁图谱周围有六个标记qKL-2区域已开发并用于精细测绘qKL-2。最后,qKL-2通过用 Zea_Mays_B73 v4 基因组进行爆破,在玉米 9 号染色体上选择重叠重组染色体,在 1.95 Mb 物理间隔中证实了这一点。转录组分析显示,在鉴定的 40 个蛋白质编码基因中,在两个亲本之间总共检测到 11 个差异表达的基因。qKL-2间隔。GRMZM2G006080 编码受体样蛋白激酶 FERONIA,被预测为控制籽粒大小的候选基因。这项工作不仅有助于了解玉米籽粒大小的遗传机制,而且为进一步精细定位甚至克隆有希望的位点奠定基础。