Fig. 4. An example of genotyping of apple cultivars using molecular tags of the MdSWEET genes that were highly expressed during fruit development.

a–h Polymorphic bands of SSR markers detected at the MdSWEET2a, MdSWEET2b, MdSWEET2d, MdSWEET2e, MdSWEET7a, MdSWEET7b, MdSWEET9b, and MdSWEET12a loci, respectively. i An agarose gel electrophoresis of PCR products derived from the first intron of MdSWEET15a, which are digested with the NdeI enzyme. Polymerase chain reactions products containing CATATG sequences can be digested, whereas PCR products with TATATG sequences cannot be digested. 1: Laidi; 2: Fulaibao; 3: Zaoshengchi; 4: Qingxiangjiao; 5: Beinaoni; 6: Fujin; 7: Qingguan; 8: Xingcheng 2310; 9: Bankeluofute; 10: Senmalan; 11: Yeweilin; 12: Kangbingjinguan 51; 13: Zhanxuan 14; 14: Xingcheng 1518; 15: Zhongxin; 16: Zhanxuan 4; 17: Hebeikangbingjinguan; 18: Jinguang; 19: Lisijin; 20: Tianhongyu