1. Pioneer Hi-Bred International, 7250 Northwest 62nd Avenue, Johnston, IA 50131, USA.
2. Diversa Corporation, 4955 Directors Place, San Diego, CA 92121, USA.
3. Department of Horticulture, Purdue University, West Lafayette, IN 47907, USA.
4. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.