Table 2_QTL-based dissection of three key quality attributes in maize using double haploid populations.docx

IntroductionMaize is a crucial source of nutrition, and the quality traits such as starch content, oil content, and lysine content are essential for meeting the demands of modern agricultural development. Understanding the genetic basis of these quality traits significantly contributes to improving maize yield and optimizing end-use quality. While previous studies have explored the genetic basis of these traits, further investigation into the quantitative trait loci (QTL) responsible for variations in starch content, oil content, and lysine content still requires additional attention.
MethodsDouble haploid (DH) populations were developed via a nested association mapping (NAM) design. Phenotypic data for starch, oil, and lysine content were collected using near-infrared spectroscopy and analyzed via ANOVA. Genotyping employed a 3K SNP panel, and genetic maps were constructed using QTL IciMapping. QTL analysis integrated single linkage mapping (SLM) and NAM approaches, with candidate genes identified via maizeGDB annotation and transcriptome data.
ResultsThe broad-sense heritability of the populations with a range of 63.98-80.72% indicated the majority of starch content, oil content and lysine content variations were largely controlled by genetic factors. The genetic maps were constructed and a total of 47 QTLs were identified. The phenotypic variation explained (PVE) of the three traits is in a range of 2.60-17.24% which suggested that the genetic component of starch content, oil content and lysine content was controlled by many small effect QTLs. Five genes encoding key enzymes in regulation of starch, oil and lysine synthesis and metabolism located within QTLs were proposed as candidate genes in this study.
DiscussionThe information presented herein will establish a foundation for the investigation of candidate genes that regulate quality traits in maize kernels. These QTLs will prove beneficial for marker-assisted selection and gene pyramiding in breeding programs aimed at developing high-quality maize varieties.

引言：玉米是重要的营养来源，其淀粉含量、含油量及赖氨酸含量等品质性状是满足现代农业发展需求的核心指标。解析上述品质性状的遗传基础，对提升玉米产量、优化终端加工品质具有重要意义。尽管已有研究对这些性状的遗传基础开展了探索，但针对淀粉含量、含油量及赖氨酸含量变异相关的数量性状位点（quantitative trait loci, QTL）的深入研究仍有待加强。
材料与方法：采用嵌套关联作图（nested association mapping, NAM）设计构建双单倍体（double haploid, DH）群体。利用近红外光谱法采集淀粉、含油量及赖氨酸含量的表型数据，并通过方差分析（Analysis of Variance, ANOVA）进行统计分析。基因分型采用3K SNP芯片，借助QTL IciMapping软件构建遗传连锁图谱。QTL分析整合了单连锁作图（single linkage mapping, SLM）与NAM方法，并通过maizeGDB数据库注释及转录组数据筛选候选基因。
结果：该群体的广义遗传力介于63.98%~80.72%之间，表明淀粉含量、含油量及赖氨酸含量的变异主要受遗传因素调控。本研究共构建了遗传连锁图谱，并鉴定出47个QTL。三个性状的表型变异解释率（phenotypic variation explained, PVE）范围为2.60%~17.24%，提示淀粉含量、含油量及赖氨酸含量的遗传调控由多个小效应QTL共同介导。本研究共筛选出5个位于QTL区间内、编码调控淀粉、油脂及赖氨酸合成代谢关键酶的基因，可作为候选基因。
讨论：本研究所得数据可为玉米籽粒品质性状调控候选基因的后续研究奠定理论基础。上述鉴定得到的QTL可为优质玉米品种培育中的标记辅助选择及基因聚合育种提供有力的技术支撑。