Molecular Plant Breeding 2025, Vol.16, No.1, 1-12 http://genbreedpublisher.com/index.php/mpb 1 Review Article Open Access Genetic Basis of Agronomic Traits in Cucumber: A Review of QTL Mapping Studies Fei Yang, Qianlu Gu, Wentao He, Decheng Hong, Mengyan Yu, Jinxiao Yao Zhoushan Academy of Agricultural Sciences, Zhoushan, 316000, Zhejiang, China Corresponding email: yjx241@126.com Molecular Plant Breeding, 2024, Vol.16, No.1 doi: 10.5376/mpb.2025.16.0001 Received: 07 Dec., 2024 Accepted: 10 Jan., 2025 Published: 19 Jan., 2025 Copyright © 2025 Yang 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: Yang F., Gu Q.L., He W.T., Hong D.C., Yu M.Y., and Yao J.X., 2025, Genetic basis of agronomic traits in cucumber: a review of QTL mapping studies, Molecular Plant Breeding, 16(1): 1-12 (doi: 10.5376/mpb.2025.16.0001) Abstract This study provides a comprehensive synthesis of the genetic basis underlying key agronomic traits in cucumber (Cucumis sativus L.), focusing on findings from quantitative trait loci (QTL) mapping studies. By analyzing over 300 QTLs across 42 traits, the review highlights the significant progress in identifying genetic markers associated with essential agronomic characteristics, including yield, fruit quality, disease resistance, and growth habits. Noteworthy discoveries include major QTLs such as Ef1.1, which influences early flowering, and FS5.2, a key regulator of fruit size and shape. These findings underscore the intricate genetic architecture governing cucumber traits and the potential for marker-assisted selection (MAS) to enhance breeding efficiency. The review also addresses challenges in the reproducibility and validation of QTLs across different genetic backgrounds and environments. Furthermore, the integration of next-generation sequencing technologies has bolstered QTL mapping precision, providing detailed genetic maps and facilitating candidate gene identification. Future directions involve leveraging gene-editing technologies like CRISPR/Cas9 and combining multi-omics approaches to further elucidate the regulatory networks underlying agronomic traits. The insights from QTL mapping not only advance cucumber breeding efforts but also set the foundation for developing resilient, high-yielding, and high-quality cucumber varieties to meet agricultural demands. Keywords Cucumber (Cucumis sativus L.); Agronomic traits; QTL mapping; Genetic basis; Disease resistance; Fruit quality; Next-generation sequencing; CRISPR/Cas9; Cucumber breeding 1 Introduction Cucumber (Cucumis sativus L.) is a globally significant vegetable crop, valued for its versatility and economic importance. It is cultivated extensively for both fresh consumption and processing purposes, contributing substantially to agricultural economies worldwide (Lee et al., 2020; Wang et al., 2020b). The crop's relatively short life cycle and self-compatible mating system make it an ideal candidate for genetic studies and breeding programs (Wang et al., 2020b). Key agronomic traits in cucumber include yield, fruit quality, and disease resistance, all of which are critical for enhancing crop performance and meeting market demands. Yield-related traits such as fruit weight, length, and diameter are essential for maximizing production efficiency (Yuan et al., 2008; Zhu et al., 2016). Fruit quality traits, including flesh thickness and skin characteristics, are vital for consumer acceptance and marketability (Yuan et al., 2008; Miao et al., 2011). Disease resistance, particularly against pathogens like powdery mildew and downy mildew, is crucial for ensuring crop health and reducing losses (Lee et al., 2020; Wang et al., 2023). These traits are the primary focus of breeding programs aimed at improving cucumber varieties (Fazio et al., 2003; Bo et al., 2014). Quantitative trait loci (QTL) mapping is a pivotal genetic tool used to identify loci associated with important agronomic traits. By linking phenotypic variation to specific genomic regions, QTL mapping facilitates the understanding of the genetic basis of complex traits (Yuan et al., 2008; Pan et al., 2017). This approach supports targeted breeding strategies, enabling the development of cucumber varieties with enhanced yield, quality, and disease resistance (Zhu et al., 2016; Wang et al., 2020b). The integration of high-density genetic linkage maps and next-generation sequencing technologies has further refined QTL mapping, making it a powerful method for genetic improvement in cucumbers (Zhu et al., 2016; Pan et al., 2022).
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