About the Authors
Institute of Evolutionary Biology and Environmental Studies, Institute of Plant Biology, and Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
The authors have declared that no competing interests exist.
Conceived and designed the experiments: TT PK KKS. Performed the experiments: TT PK C-LY JBB KKS. Analyzed the data: TT PK KKS. Wrote the paper: TT PK JBB KKS.