1. Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695
2. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE–901 83 Umea, Sweden
3. Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany Academy of Sciences of the Czech Republic, CZ–783 71 Olomouc, Czech Republic
4. State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China