1. Institute of Biology I, Plant Physiology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany, Institute of General Botany, Johannes Gutenberg-University Mainz, Saarstrasse 21, 55099 Mainz, Germany, and Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Krakow, Poland