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

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 C2) 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 C2 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 C2 locus-linked ClPPR-based marker (M7). As a result, dominant alleles at the C2 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 C2 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.

Genetic Tapestry of Capsicum Fruit Colors: A Comparative Analysis of Four Cultivated Species

“…A QTL analysis in melon (Cucumis melo) identi ed a PPR gene (CmPPR1) as the candidate gene for the esh phenotype, and this locus represents one of the two signi cant loci that control fruit esh color in melon(Galpaz et al 2018). A recent genetic mapping study showed that the C 2 locus controlling yellow esh color in watermelon is cosegregated with the marker derived from a PPR gene, indicating a vital role of PPR genes in regulating fruit color in diverse species(Park et al 2023). In the current study, we have identi ed 12 PRR gene isoforms associated with either of the color spaces in the study.…”