Construction of a genetic map for Citrullus lanatus based on CAPS markers and mapping of three qualitative traits

Two-hundred-twenty-five BC1 generations were obtained from backcrossing F1 of the shallow green rind, red flesh, no bitterness cultivated watermelon inbred line W1-1 and the dark green rind, white flesh, bitter wild species PI186490 hybrid as well as their female parents. CAPS makers spanning the whole genome were used to genotype every individual based on whole-genome resequencing data. Watermelon genetic linkage maps of 186 CAPS markers corresponding to 11 chromosomes were constructed, spanning a total distance of 1468.09 cM. Genetic analysis and gene mapping were performed using the flesh color, rind pattern and flesh bitterness as 3 qualitative traits. The results showed that wide rind stripes and flesh bitterness were controlled by a dominant gene, with red flesh recessive to white flesh, and 3 loci were identified related to the 3 fruit traits mentioned above. This study provides a theoretical basis for molecular marker-assisted selection of desirable watermelon fruit traits.