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Research Article

Identification of a Novel Major QTL on Chromosome 5 Controlling Female Flowering Frequency in Watermelon
Dong-Hyeon Min1
,
Yoon Jeong Jang1
,
Yong-Jae Kim2
,
Gung Pyo Lee1*
1Department of Plant Science and Technology, Chung-Ang University, Ansung 17546, Korea
2Partner Seed Co., Ltd., Gimje 54324, Korea
*Corresponding Author
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Abstract

Female flowering frequency is a critical determinant of fruit yield and concentrated harvest outcomes in watermelon (Citrullus lanatus). Although the genetic mechanisms governing sex forms (e.g., monoecy vs. andromonoecy) are well established, quantitative regulation of the female flower node frequency remains largely underexplored. In this study, we investigated the genetic architecture of the female flowering index (FFI) using an F2 segregating population derived from a cross between a high-female-flowering-frequency line, ‘DAPFF01’, and a low-female-flowering-frequency line, ‘A0228’. A phenotypic analysis of the F2 population revealed a continuous distribution with transgressive segregation, indicating that FFI is a quantitative trait controlled by polygenic factors. To identify the genomic regions governing this trait, we employed a combined approach involving bulked segregant analysis sequencing (BSA-seq) and high-density genotyping-by-sequencing linkage mapping. We identified a novel major quantitative trait locus (QTL), qFFI5.1, located on chromosome 5 within a physical interval of approximately 294 kb (28.66–28.96 Mb), showing a peak logarithm of the odds score of 10.47. This locus is distinct from the previously characterized sex-determination loci on chromosomes 3 and 6. High-resolution melting markers developed for single-nucleotide polymorphisms within the candidate region showed co-segregation rates in the range of 71.9–77.5% with the phenotype, validating the robustness of the QTL. Annotation of the genomic interval revealed putative candidate genes encoding MYB transcription factors and auxin-responsive proteins, suggesting that a regulatory pathway is potentially involved in auxin signaling. These findings provide new insights into the genetic control of flowering habits in watermelon and offer knowledge of valuable molecular markers for marker-assisted selection in breeding high-yield cultivars.

Keywords
bulked segregant analysis
high-resolution melting
linkage mapping
marker assisted selection
next-generation sequencing
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Information
  • Publisher :KOREAN SOCIETY FOR HORTICULTURAL SCIENCE
  • Publisher(Ko) :한국원예학회
  • Journal Title :Horticultural Science and Technology
  • Journal Title(Ko) :원예과학기술지
  • Received Date : 2026-01-06
  • Accepted Date : 2026-01-08
  • DOI :https://doi.org/10.7235/HORT.20260002
Journal Informaiton Horticultural Science and Technology Horticultural Science and Technology
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