Watermelon and melon are important members of the Cucurbitaceae family, offering high economic benefit and nutritional value. With the release and ongoing refinement of the watermelon and melon genomes, many target genes (or loci) for further biology regulation exploration and molecular breeding, have been identified. Herein, we describe recent progress in genetic mapping and molecular regulation mechanisms for fruit quality, fruit development, plant morphogenesis, and plant disease resistance. We further outline future research priorities and breeding frameworks for watermelon and melon. This review delineates molecular regulators of fruit and plant development, offering a framework to explore homologous mechanisms in other Cucurbitaceae members.

Stigma color plays an important role in pollination. In nature, melon (Cucumis melo L.) stigmas are either yellow or green; however, a review of the literature found no report on how stigma color affects pollination and fruit development in melon. Here, we used an F₂ melon population derived from a cross between 'MR-1' (P₁, with green stigmas) and 'M1–32' (P₂, with yellow stigmas), and performed genetic analysis and mapping. The results of bulked segregant analysis allowed the identification of genetic loci controlling stigma color on chromosomes 6 and 8. An F₂ population consisting of 150 individuals was used for initial mapping. A genetic map of 304.17 cM was constructed using 37 cleaved amplified polymorphism sequence (CAPS) markers. We identified one major quantitative trait locus (QTL) and one minor QTL for stigma color. The major QTL GS8.1 was further mapped to a 4.13 cM interval between CAPS markers 8C-10 and 8C-16, which explained 27.04% of the phenotypic variation. In addition, GS6.1 was mapped between E-49 and 6A-7, explaining 18.6% of the phenotypic variation. This study provides a theoretical basis for the fine mapping and cloning of melon genes controlling stigma color.