1. Department of Biotechnology, Indian Institute of Technology-Madras, Chennai, India 600036 (T.B., N.L., H.B., R.B.);
2. Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, CH–8008 Zurich, Switzerland (C.S., C.E., U.G.); and
3. Institute of Mathematics, University of Zürich, CH–8057 Zurich, Switzerland (F.G.)