1 Laboratory of Plant Physiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands. l.j.de.kok@rug.nl.
2 Department of Botany and Plant Sciences, University of California, Riverside, Parlier, 93648, CA, USA. dagrantz@ucanr.edu.
3 U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research, Department of Crop Science, North Carolina State University, 3127 Ligon Street, Raleigh, 27607, NC, USA. kent.burkey@ars.usda.gov.