Fine mapping and candidate gene analysis of McFPL1 regulate fruit pedicel length in bitter gourd (Momordica spp.)

With the advancement of agricultural mechanization, the development of crop varieties suitable for mechanized harvesting has become an important breeding objective. In bitter gourd (Momordica charantia), increasing fruit pedicel length (FPL) is considered a key trait for improving harvest efficiency. However, the genetic and molecular mechanisms controlling FPL remain largely unknown. In this study, two contrasting lines, 23S083 (long FPL), and 23S184 (short FPL), were selected for comparison. Microscopic analysis revealed that the longer pedicel in 23S083 was attributable to both increased cell length and number compared to 23S184. Using F1 and F2 populations derived from these parents, the major locus McFPL1 was initially mapped to a 2.46 Mb region on chromosome 3 through BSA-seq. Fine mapping with 15 polymorphic markers further narrowed the candidate region to 255.059 kb. Among the 21 genes with mutations in this interval, Moc03g21510, which encodes an ABCG subfamily ATP-binding cassette transporter, was proposed as the most promising candidate gene. During the elongation of the fruit pedicel, the expression level of this gene was significantly higher in 23S083 than in 23S184. Sequence analysis identified 20 SNPs and eight InDels in its 3'UTR, suggesting that these variations may influence mRNA stability and thus regulate pedicel elongation. Furthermore, the co-segregating marker developed from these variations accounted for approximately 76.7% of the phenotypic variation in FPL within the natural bitter gourd population. These results provide valuable genetic insights into FPL formation and will facilitate the molecular breeding of mechanization-adapted bitter gourd varieties.