1. University of Zürich, Institute of Plant Biology, CH–8008 Zurich, Switzerland (U.G.S., A.E., S.S., A.B., M.S., E.M.); Swiss Federal Institute of Technology, Institute of Plant Science, CH–8092 Zurich, Switzerland (S.B.); Zürich-Basel Plant Science Center, CH–8092 Zurich, Switzerland (U.G.S., S.B., A.E., S.S., A.B., M.S., E.M.); Technical University of Kaiserslautern, Plant Physiology, D–67653 K