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 F_2:3 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 F_2:3 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.

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。