1. Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
2. French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institute for Desert Research, Ben Gurion University, Sede-Boqer Campus 84990, Israel
3. Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, New York 14853
4. Department of Plant Sciences, University of California-Davis, Davis, California 95616