Kernel width (KW) is a key determinant of kernel weight and an important selection trait during the maize domestication and improvement. KW is a complex quantitative trait that is controlled by many quantitative trait loci (QTL) with minor effects, but the underlying genes for KW using natural variation remain rarely reported in maize. In this study, using advanced backcross populations from the cross of Huangzaosi (HZS, recurrent parent) × YE478 (donor parent), a major QTL responsible for KW previously reported, qKW7, were divided into two tightly linked loci with opposite genetic effects, qKW7a and qKW7b. Further, a near isogenic line (NIL) of qKW7b^YE478 with the HZS background was developed by molecular marker-assisted selection (MAS). Using a large segregation population developed from the NIL and its recurrent parent, qKW7b was fine mapped to a physical interval of 59 kb. By the assembled genome collinearity analysis in the qKW7b region, redundant genomic structural variations which included insertions, deletions, and inversions were determined. A putative zinc finger homeodomain transcription factor gene, Zm00001d020460, was supposed to be the candidate gene responsible for qKW7b. Quantitative real-time PCR showed that Zm00001d020460 was differently expressed during early kernel development between the qKW7b NILs, indicating that this gene might be a causal gene of qKW7b. This result enriches our knowledge of the genetic basis for KW and paves a new way to efficiently improve KW through functional marker in maize germplasm.

籽粒宽度（KW）是决定玉米粒重的重要因素，也是玉米驯化和改良过程中重要的选择性状。KW是一个复杂的数量性状，受许多数量性状基因座（QTL）控制，但影响不大，但是利用自然变异的KW潜在基因在玉米中仍然鲜有报道。在这项研究中，使用了先前报道的负责KW的主要QTL q枣7，即来自黄枣寺（HZS，轮回亲本）×YE478（捐助父本）的杂交回交群体，将其分为两个紧密连锁的具有相反遗传效应的基因座qKW7a。和qKW7b。此外，qKW7b ^YE478的近等基因系（NIL）具有HZS背景的分子标记辅助选择（MAS）。使用从NIL及其后代产生的大量隔离种群，将qKW7b精细映射到59 kb的物理间隔。通过在qKW7b区的组装基因组共线性分析，确定了冗余的基因组结构变异，包括插入，缺失和倒位。假定的锌指同源结构域转录因子基因Zm00001d020460被认为是负责qKW7b的候选基因。实时定量PCR显示Zm00001d020460在qKW7b之间的早期内核发育过程中表达不同NILs，表明该基因可能是qKW7b的因果基因。该结果丰富了我们对小麦遗传基础的认识，为通过玉米种质中功能标记物有效改良小麦提供了新途径。