About the Authors
Institute of Plant Biology, University of Zürich, Zürich, Switzerland
Zürich-Basel Plant Science Center, ETH Zürich, Zürich, Switzerland
The authors have declared that no competing interests exist.
The author(s) have made the following declarations about their contributions: Conceived and designed the experiments: ABD UG. Performed the experiments: ABD. Analyzed the data: ABD DSL. Contributed reagents/materials/analysis tools: AN CMF ST. Wrote the paper: ABD UG.