1. Plant Ecophysiology, Department of Biology, Utrecht University, 3584 CH Utrecht, the Netherlands
2. Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
3. Department of Biology, Duke University, Durham, North Carolina 27278, USA
4. Department of Plant Biology, College of Biological Sciences, University of California, Davis, California 95616, USA