Next-generation sequencing-based QTL mapping for unravelling causative genes associated with melon fruit quality traits

High resolution QTL mapping of genetic factors affecting fruit quality traits in melon (Cucumis melo) was achieved in two projects. Next-generation sequencing (NGS), coupled with unique genetic materials, was used to attain high resolution mapping, in both studies. The first project was based on the RNA-seq of mature fruits of a Recombinant Inbred Lines (RIL) population derived from a cross between PI 414723 and 'Dulce'. The second project was based on genotyping-by-sequencing (GBS) analyses of F3 plants derived from a cross between 'Noy Amid' and 'Dulce'. In each project, QTL analysis was conducted using approximately 60,000 SNP markers that were detected by either GBS or RNA-seq. In the first project, phenotyping and metabolic profiling included fruit quality traits associated with taste, aroma and color while the second project focused on flesh and rind color, ethylene and the formation of the fruit abscission zone. Evidence of the high resolution of the analysis was provided in cases where QTLs for selected fruit traits were mapped to an interval of 120 genes that included the known underlying causative genes. These cases included genes associated with the accumulation of specific aroma volatiles and fruit fleshcolor.