1. Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Center for Plant Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China.
2. State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Academy of Seed Design, Chinese Academy of Sciences, 100101 Beijing, China.
3. Max Planck Institute for Plant Breeding Research, Cologne, Germany.
4. Institute of Biochemistry, University of Cologne, Zuelpicher Strasse 47, 50674 Cologne, Germany.