Validation of QTLs for δ13C under drought-stressed conditions, based on genotyping using KASP assay-based SNP markers. a genotype plot on 3 positions (lm1712, np2623, and np2691) for KASP platform. b phenotypic distribution of δ13C measured in HC × QG segregating population under drought-stressed conditions, based on 3 stable positions (lm1712, np2623, and np2691). lm, ll, nn, and np represent genotypes detected by RAD-SNP marker genotyping. Base pairs represent genotypes detected by KASP array. Significance levels of differences at p < 0.05 and p < 0.01 are indicated with “*” and “**”, respectively. c genotypes of 7 commercial apple cultivars on 3 stable positions (lm1712, np2623, and np2691), as detected by KASP assay. Phenotypic values of δ13C in several cultivars under drought-stressed conditions were reported by Liu et al.