Construction of a high-density genetic map and the soluble solid content gene <i>BhSSC10.1</i> in wax gourd (<i>Benincasa hispida</i>)

The soluble solids content (SSC) of wax gourd is a pivotal intrinsic fruit quality trait. However, limited studies concerning the associated genes have been documented. In this investigation, 105 recombinant inbred line (RIL) populations derived from GX-7 and MY-1 served as the research material. A high-density genetic map of wax gourd was constructed, incorporating 956 bin markers distributed across 12 linkage groups (LGs). These markers were obtained via whole-genome resequencing, yielding 1,256,985 high-quality SNPs and indels. The total map spanned 1,357.15 cM, with an average inter-marker distance of 1.53 cM. Utilizing this map in conjunction with wax gourd SSC phenotypic data, two quantitative trait loci (QTLs) were identified on Chr5 and Chr10. Notably, <i>qSSC10</i> exhibited a high contribution and effect value, encompassing 31 annotated genes within this interval. Subsequently, we screened ten genes within <i>qSSC10</i> based on biparental polymorphism analysis. Among these genes, one encoding Class III peroxidase, <i>Bch10G006650</i> (<i>BhSSC10.1</i>), demonstrated highly significant expression differences between the parental lines. Consequently, <i>BhSSC10.1</i> emerges as a promising candidate gene for regulating the SSC in wax gourd. The findings of this study established a theoretical foundation for elucidating the roles of SSC-related genes and the development of high-quality wax gourd varieties.