1. USDA-ARS, Western Regional Research Center, Genomics and Gene Discovery Research Unit, Albany, CA 94710, USA, 2Department of Plant Sciences, University of California, Davis, CA 95616, USA, 3Bioengineering College, Campus A, Chongqing University, Chongqing 400030, China, 4USDA-ARS, Western Regional Research Center, Crop Improvement and Utilization Research Unit, Albany, CA 94710, USA and 5Energy Biosciences Institute, University of California, Berkeley, CA 94720, USA