1. Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
2. Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture; Huazhong Agricultural University; Wuhan 430070 People's Republic of China
3. Huazhong Agricultural University; Wuhan 430070 People's Republic of China
4. National Center for Vegetable Improvement (Central China); Wuhan 430070 People's Republic of China
5. Biochemistry Division, Department of Biology; Friedrich-Alexander-University Erlangen-Nuernberg; 91058 Erlangen Germany