Identification and comparative analysis of quantitative trait loci associated with parthenocarpy in processing cucumber

Parthenocarpy (seedless fruit) is an economically important yield-related trait in cucumber (Cucumis sativus L.; 2n = 2x = 14). However, the genomic locations of factors controlling parthenocarpic fruit development in this species are not known. Therefore, an F-2 : 3 mating design was utilized to map quantitative trait loci (QTL) for parthenocarpy using a narrow cross employing two gynoecious, indeterminate and normal leaf lines [2A (parthenocarpic) and Gy8 (non-parthenocarpic)]. QTL detection was performed employing 2A- and Gy8-coupling phase data using the parthenocarpic yield of 126 F-3 families grown at two locations at Hancock, WI in 2000. The QTLs detected in this study were compared with the map locations of QTLs conditioning first-harvest yield of seeded cucumber characterized in a previous study. There were 10 QTLs for parthenocarpy detected defining four genomic regions, in which three QTLs also mapped to the same genomic regions as QTLs detected for fruit yield at first-harvest as reported in a previous study. The eight fluorescence amplified fragment length polymorphism (AFLP) markers linked to parthenocarpy through QTL mapping defined herein (four each in linkage groups 1 and 4) are candidates for use in marker-assisted selection programmes where breeding for increased levels of parthenocarpy is an objective in the elite-processing cucumber populations.