Identification of a novel locus C2 controlling canary yellow flesh color in watermelons

Girim Park; Durre Shahwar; Gaeun Jang; Jagyeong Shin; Gibeom Kwon; Younjae Kim; Chang Oh Hong; Bingkui Jin; Hoytaek Kim; Oakjin Lee; Younghoon Park

doi:10.3389/fgene.2023.1256627

Identification of a novel locus C₂ controlling canary yellow flesh color in watermelons

Front Genet. 2023 Sep 19:14:1256627. doi: 10.3389/fgene.2023.1256627. eCollection 2023.

Authors

Girim Park^#¹, Durre Shahwar^#¹, Gaeun Jang¹, Jagyeong Shin¹, Gibeom Kwon², Younjae Kim², Chang Oh Hong^{3

4}, Bingkui Jin⁵, Hoytaek Kim⁶, Oakjin Lee⁷, Younghoon Park^{1

4}

Affiliations

¹ Department of Horticultural Bioscience, Pusan National University, Miryang, Republic of Korea.
² Partner Seeds Co., Ltd., Gimje, Republic of Korea.
³ Department of Life Science and Environmental Biochemistry, Pusan National University, Miryang, Republic of Korea.
⁴ Life and Industry Convergence Research Institute, Pusan National University, Miryang, Republic of Korea.
⁵ UNELL Biotechnology Co., Ltd., Weifang, China.
⁶ Department of Horticulture, Sunchon National University, Sunchon, Republic of Korea.
⁷ National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju, Republic of Korea.

^# Contributed equally.

Abstract

The flesh color of watermelon is an important trait that is determined by carotenoid composition and affects consumers' fruit desirability. Although a complete dominant control by C locus (Cllcyb) for canary yellow flesh (CY) over red flesh has been reported, red and CY colors frequently appear as a mixed pattern in the same flesh (incomplete canary yellow, ICY) in F₁ and inbred lines carrying dominant C alleles. Therefore, we examined the genetic control of the mixed color pattern in ICY using whole-genome resequencing of three ICY (ICY group) and three CY inbred lines (CY group), as well as genetic linkage mapping of an F₂ population. The segregation pattern in 135 F₂ plants indicated that CY is controlled by a single locus (named C ₂) dominant over ICY. The whole-genome resequencing of ICY and CY inbred lines revealed an ICY/CY-specific region of approximately 27.60-27.88 Mb on Chr. 2 that was polymorphic between the ICY and CY groups. Our genetic map, using nine cleaved amplified polymorphic sequence markers developed based on the single-nucleotide polymorphisms from the ICY/CY-specific region, confirmed that C ₂ is located on Chr. 2 and cosegregated with the marker (M7) derived from a non-synonymous single-nucleotide polymorphism of the pentatricopeptide repeat (PPR) gene (ClPPR, Cla97C02G039880). Additionally, 27 watermelon inbred lines of ICY, CY, and red flesh were evaluated using previously reported Cllcyb (C locus)-based markers and our C ₂ locus-linked ClPPR-based marker (M7). As a result, dominant alleles at the C ₂ locus were required to produce CY, in addition to dominant alleles at the C locus, while a recessive homozygous genotype at the C locus gave the red flesh irrespective of the genotype at the C ₂ locus. Using a ClPPR-based cleaved amplified polymorphic sequence developed in this study and Cllcyb-based markers, watermelon cultivars with CY, ICY, and red flesh could be successfully discerned, implying that the combined use of these markers will be efficient for marker-assisted selection of flesh color in watermelon breeding.

Keywords: Citrullus lanatus; flesh color; marker-assisted selection; pentatricopeptide repeat; watermelon.

Grants and funding

The authors declare that financial support was received for the research, authorship, and/or publication of this article. This study was supported by a grant (project no. PJ014846012020) from the National Institute of Horticultural Herbal Sciences, Rural Development Administration.