1. College of Horticulture, Northwest A & F University, Yangling 712100, P.R. China
2. Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, P.R. China
3. Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture and Rural Affairs, Guangzhou 510640, P.R. China
4. Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Guangzhou 510640, P.R. China
5. Howard Hughes Medical Institute, Duke University, Durham, North Carolina 27708, United States
6. Department of Biology, Box 90338, Duke University, Durham, North Carolina 27708, United States
7. Institute of Fruit and Floriculture Research, Gansu Academy of Agricultural Sciences, Anning, Lanzhou 730070, P.R. China