A high-density SNP linkage map reveals a major LG3 QTL hotspot controlling early-maturity–related traits in ridge gourd (Luffa acutangula)

Introduction Early maturity is an important breeding target in ridge gourd ( Luffa acutangula ), but its genetic basis remains poorly understood. Methods An F 2 population of 147 plants was developed from a cross between two parental lines contrasting in early maturity and evaluated for six related traits. Whole-genome resequencing of the parents and 144 retained F₂ individuals was used for SNP discovery, binning, high-density linkage-map construction, and QTL analysis. Results A high-density genetic linkage map containing 4,035 representative bin markers across 13 linkage groups was constructed. Eight significant QTLs were identified, most of which clustered on LG3 and formed a major multi-trait hotspot. The hotspot was anchored to a 7.03 Mb interval on chromosome 3 containing 136 annotated genes. Lac03g1231 and Lac03g1281 were prioritized as biologically plausible candidates. Discussion These results provide a genetic framework for dissecting early maturity in ridge gourd and support future fine mapping, developmental-stage expression analysis, functional validation, and marker-assisted breeding.