BSA-seq based genetic mapping of gynoecy regulating gene(s) in sponge gourd (Luffa cylindrica L)

Gynoecy is an important reproductive trait for enhancing hybrid seed production efficiency and yield potential in sponge gourd ( Luffa cylindrica L.). Despite its breeding significance, the genetic mechanism underlying gynoecious sex expression in this crop remains largely unexplored. Therefore, the present study investigated the inheritance pattern, genomic localization, linkage analysis and putative candidate genes of gynoecy using segregating populations derived from a cross between the gynoecious line PGY-10 and the monoecious line PSG-223. Phenotypic evaluation of F 2 , F 2:3 progenies and backcross populations demonstrated that gynoecy is governed by a single recessive gene. Bulked segregant analysis of 169 F 2 plants combined with whole-genome resequencing identified a major genomic region associated with gynoecy on chromosome 11 of the Luffa_cylindrica_var_P93075_v1 reference genome. Linkage analysis using 17 polymorphic Kompetitive Allele-Specific PCR (KASP) markers further delimited the gynoecy-associated locus, SG_gy11 , to a 1.43 Mb interval flanked by markers SGMJP_1854186 (1.43 cM) and SGMJP_3281262 (3.71 cM). Gene annotation within the mapped interval identified six putative candidate genes associated with reproductive development and hormone-mediated pathways, suggesting their possible involvement in gynoecious sex expression. This study provides the first genetic evidence of a major recessive gene controlling gynoecy in sponge gourd and identifies closely linked KASP markers for marker-assisted selection. The identified genomic region and candidate genes provide valuable resources for dissecting the molecular regulation of sex expression and accelerating the development of gynoecious parental lines for hybrid breeding programs in sponge gourd.