1. Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom (I.F., W.H., L.J.S.)
2. Department of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany (I.F., A.-C.K., D.L.); and
3. Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany (A.N.-N., P.A.P., A.R.F.)