1. National Maize Improvement Center, Key Laboratory of Crop Heterosis and Utilization, the Ministry of Education, Key Laboratory of Crop Genetic Improvement, Beijing Municipality, Center for Crop Functional Genomics and Molecular Breeding, College of Agronomy and Biotechnology, China Agricultural University, Beijing 10093, P. R. China
2. Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, Plant and Microbial Biology Department, University of California at Berkeley, CA 94710, USA
3. State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 10093, P. R. China
4. Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA
5. Department of Plant Biology, Department of Horticulture, Michigan State University, East Lansing, MI 48824 USA