1. Department of Physics & Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands; Krebbs Institute for Biomolecular Research and Robert Hill Institute for Photosynthesis, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, U.K.; Department of Plant Nutrition, Estacion Experimental de Aula Dei (CSIC), Apartado 202, Zaragossa 50080, Spain; and Department of Botany, University of Glasgow, Glasgow G12 8QQ, U.K.