About the Authors
Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
Plant Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America
The authors have declared that no competing interests exist.
SB and DW conceived and designed the experiments. JL, SB, SS, AS, and MS performed the experiments. JL, SB, and DW analyzed the data and wrote the paper.