Maize Genomics and Genetics 2025, Vol.16, No.6, 316-324 http://cropscipublisher.com/index.php/mgg 316 Feature Review Open Access Identification of QTLs Associated with Silk Emergence Time Under Heat Stress Delong Wang, Jiamin Wang, Yunchao Huang Hainan Provincial Key Laboratory of Crop Molecular Breeding, Sanya, 572025, Hainan, China Corresponding author: yunchao.huang@hitar.org Maize Genomics and Genetics, 2025, Vol.16, No.6 doi: 10.5376/mgg.2025.16.0029 Received: 12 Oct., 2025 Accepted: 27 Nov., 2025 Published: 17 Dec., 2025 Copyright © 2025 Wang et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wang D.L., Wang J.M., and Huang Y.C., 2025, Identification of QTLs associated with silk emergence time under heat stress, Maize Genomics and Genetics, 16(6): 316-324 (doi: 10.5376/mgg.2025.16.0029) Abstract The Silk Emergence Time (SET) is a critical period for the formation of corn (Zea mays L.) grains. Especially under high-temperature stress conditions, its coordination is of great significance for successful pollination and stable yield. High temperatures often lead to delayed filaments and failed pollination, seriously affecting the final yield. This study, with QTL mapping at its core, systematically analyzed the genetic and physiological mechanisms affecting the silk production period under high-temperature stress, providing theoretical support and genetic resources for the molecular breeding of heat-tolerant corn. Analyze the genetic regulatory mechanism of SET and the role of hormone signaling pathways in the heat hypochondrium response; Evaluate the effects of agronomic factors such as plant height and ASI on SET variations; Precise QTL localization is carried out by using the combined method of genomics and transcriptomics. Screen key candidate genes and conduct functional verification; Compare the differences and stability of QTLS in different thermal ecological zones through regional cases; And explore the practical application paths of QTL in heat-resistant breeding. This study reveals the genetic basis for the regulation of the silk production period of corn under high-temperature stress, providing potential targets for marker-assisted selection (MAS) and genomic selection (GS), and is conducive to the breeding of corn varieties with strong high-temperature adaptability and high yield stability. Keywords Zeamays L.; Silk emergence time; Heat stress; Quantitative trait loci (QTL) mapping; Stress-resilient breeding 1 Introduction Whether the yield of corn is high or not often depends on whether the filaments can emerge in time. The seed setting rate is closely related to the appearance of filaments, especially during the pollination period. Although we often use the "flower-silk interval (ASI)" to measure the synchronization degree of pollen and filaments, once this indicator becomes longer, pollination is prone to problems, resulting in less grain production and a decline in yield, especially under adverse conditions such as heat and drought (Dong et al., 2023). However, not all traits can be so clearly associated. For instance, filaments acceptability, pollen viability and ASI, although all are linked to yield, are greatly influenced by the environment in actual field performance, and sometimes there are exceptions. During the flowering period when heat waves hit, it's very easy for the stamens and pollen to "not match". If the filaments fail to develop, the pollen matures slowly, lacks vitality, and the condition of the filaments deteriorates, the entire pollination process may be disrupted, ultimately resulting in fewer grains and reduced yields. Some literatures even point out that during severe high temperatures, the yield loss can exceed 70% (Wang et al., 2019; 2020; 2022). Moreover, the most vulnerable period is the first few days after the silk production ends, when the plants are the most vulnerable. When high temperatures rise, reactive oxygen species (ROS) accumulate in the filaments, preventing the pollen tubes from continuing to grow and even directly leading to infertility (Gong et al., 2024). This kind of heat sensitivity during the reproductive stage is ultimately closely related to the genetic basis. Heat tolerance is not determined by one or two genes, but is a complex trait controlled by multiple genes. Therefore, it is a crucial step to identify the quantitative trait loci (QTLS) that can affect filaments appearance, ASI, and even yield performance. In recent years, many QTL mapping and GWAS studies have identified relevant genomic regions and candidate genes. These achievements not only broaden our understanding of heat stress responses but also provide underlying resources for future marker-assisted breeding and the development of more heat-resistant corn varieties.
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