1. 2Departments of Agronomy and of Zoology/Genetics, Iowa State University, Ames, Iowa 50011–1010 USA;
2. 3Maltagen Forschung GmbH, Schaarstrasse 1, D‐56626 Andernach, Germany;
3. 4Pflanzenphysiologie, Fachbereich Biologie/Chemie, Universitat Osnabruck, D‐49069, Germany;
4. 5Technische Universität München, Lehrstuhl für Botanik, Biologikum‐Weihenstephan, Am Hochanger 4, D‐85350 Freising, Germany; and
5. 6USDA‐ARS‐CICGR Unit and Departments of Agronomy and of Zoology/Genetics Iowa State University, Ames, Iowa 50011–1010 USA