Ear tip-barrenness (ETB) phenotype threatens crop yield, since it reduces the kernel number per ear. The genetic basis of ETB in maize remains largely unknown. Herein, a genome-wide association study (GWAS) and quantitative trait loci (QTL) mapping were jointly applied to identify the significant genetic loci interrelated with ETB. Six significant SNPs were detected at a stringent P-value threshold (1.95 × 10-6 ). Additionally, four environment-stable SNPs were co-detected across a single environment and best linear unbiased prediction (BLUP) model at a less stringent P-value threshold (1 × 10-4 ). The above ten SNPs were closely linked to six candidate genes, which mainly involved seed development, photosynthesis and ethylene response. Moreover, the ratio of superior allele at each significant SNP ranged from 0 to 83.33% in 30 investigated maize elite lines. QTL mapping identified fourteen QTL with phenotypic variation explained (PVE) ranging from 3.64 to 7.09%, of which one QTL (qETB2-1) was repeatedly identified in two environments. Combined analysis of GWAS and QTL mapping showed that one SNP (PZE-102175229, chromosome 2: 217 66 Mb) was located in the QTL (qETB2-2, chromosome 2: 215 90-217 82 Mb). Eighteen gene models situated in the linkage disequilibrium (LD) region of the co-localized SNP were further used to evaluate their correlation with ETB by candidate gene association analysis. Two superior haplotypes and two superior alleles were detected among 74 lines for Zm00001d007195, Zm00001d007197 and Zm00001d007201. These results provide more information for clarifying the molecular mechanism of ETB and for speeding up the genetic improvement of maize varieties. This article is protected by copyright. All rights reserved.

中文翻译：

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全基因组关联研究和 QTL 定位揭示玉米耳尖不育的遗传结构

耳尖贫瘠 (ETB) 表型威胁作物产量，因为它减少了每只穗的籽粒数。玉米中 ETB 的遗传基础在很大程度上仍然未知。在此，联合应用全基因组关联研究（GWAS）和数量性状基因座（QTL）作图来鉴定与 ETB 相关的重要遗传基因座。在严格的 P 值阈值 (1.95 × 10-6 ) 下检测到六个重要的 SNP。此外，在单个环境和最佳线性无偏预测 (BLUP) 模型中，以不太严格的 P 值阈值 (1 × 10-4) 共同检测到四个环境稳定的 SNP。上述10个SNP与6个候选基因密切相关，主要涉及种子发育、光合作用和乙烯反应。此外，每个显着 SNP 的优等位基因比例范围为 0 到 83。30 个调查的玉米优良品系中的 33%。QTL定位确定了14个具有表型变异解释（PVE）范围从3.64%到7.09%的QTL，其中一个QTL（qETB2-1）在两种环境中被重复识别。GWAS和QTL作图联合分析表明，1个SNP（PZE-102175229，2号染色体：217 66 Mb）位于QTL（qETB2-2，2号染色体：215 90-217 82 Mb）。位于共定位 SNP 连锁不平衡 (LD) 区域的 18 个基因模型被进一步用于通过候选基因关联分析评估它们与 ETB 的相关性。在 Zm00001d007195、Zm00001d007197 和 Zm00001d007201 的 74 个品系中检测到两个优越的单倍型和两个优越的等位基因。这些结果为阐明ETB的分子机制和加快玉米品种遗传改良提供了更多信息。本文受版权保护。版权所有。