叶夹角(Leaf Angle, LA)是决定玉米株型结构和光能利用效率的关键性状。在高密度种植模式成为玉米增产的主流背景下,解析不同密度下叶夹角的遗传基础,对选育耐密高产、株型优良的玉米新品种具有重要意义。本研究利用包含200份玉米自交系的关联群体,在5个环境中分别设置高密度(67,500株/hm2)和低密度(45,000株/hm2)两种种植方式,并对穗上第一片叶的LA进行调查。基于覆盖全基因组的125万个单核苷酸多态性(Single Nucleotide Polymorphism, SNP)标记,采用五种模型进行全基因组关联分析。结果表明,LA呈连续变异且近似正态分布,为数量性状。广义遗传力在高、低密度下分别为0.90和0.84。全基因组关联分析共检测到48个显著的数量性状核苷酸(Quantitative Trait Nucleotide, QTN),基于连锁不平衡衰减距离(~50 Kb),共涉及39个数量性状位点(Quantitative trait locus, QTL)和143个基因,其中107个基因仅在高密度下被检测到,提示其可能特异响应密植下的LA。通过基因本体(Gene Ontology, GO)富集分析、基因表达模式及连锁不平衡分析,最终确定Zm00001d011966为关键候选基因,该基因编码一个泛素结合酶E2,推测其通过参与生长素信号通路调控叶枕细胞发育进而影响叶夹角。单倍型分析进一步发现,该基因的优异单倍型Hap1相较于Hap2可显著减小叶夹角。综上,本研究阐明了不同种植密度下玉米穗上叶LA的遗传基础,为耐密理想株型玉米的分子育种提供了理论依据与基因资源。

Leaf angle (LA) is a critical agronomic trait that determines plant architecture and light use efficiency in maize. Given that high-density planting is a primary strategy for enhancing yield, dissecting the genetic basis of LA under varying densities is crucial for breeding elite varieties with superior density tolerance and ideal plant architecture. In this study, an association panel of 200 maize inbred lines was phenotyped for the LA of the uppermost ear leaf across five environments under high-density (67, 500 plants/hm2) and low-density (45, 000 plants/hm2) conditions. A genome-wide association study (GWAS) was conducted using 1.25 million single nucleotide polymorphism (SNP) markers and five statistical models. LA was characterized as a quantitative trait with continuous variation and an approximately normal distribution, exhibiting broad-sense heritability (0.90 and 0.84 under high and low densities, respectively). GWAS detected 48 significant quantitative trait nucleotides (QTNs), which were consolidated into 39 quantitative trait loci (QTLs) based on the linkage disequilibrium (LD) decay distance of 50 kb. These QTLs encompassed 143 candidate genes, with 107 identified specifically under high-density condition, suggesting their specialized roles in responding to dense planting. By integrating Gene Ontology (GO) enrichment analysis, expression profiling, and LD analysis, Zm00001d011966 was prioritized as a key candidate gene. This gene encodes a ubiquitin-conjugating enzyme (E2), which is hypothesized to influence LA by participating in the auxin signaling pathway to regulate pulvinus cell development. Furthermore, haplotype analysis revealed that the elite haplotype Hap1 conferred a significantly smaller LA. In summary, this study elucidates the genetic architecture of ear leaf LA under different planting densities, providing a theoretical foundation and valuable gene resources for the molecular breeding of density-tolerant maize varieties with ideal plant architecture.

国家自然科学基金联合基金项目（U21A20210），中国博士后科学基金面上资助（2020M682295、2025M773989）、河南省杰出青年基金（252300421036）、河南省重点研发专项项目（241111114300、251111111000）、河南省河南省农业良种联合攻关项目（2022010204）