1. Howard Hughes Medical Institute, Ann Arbor, Michigan 48109, United States
2. Department
of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
3. Department
of Horticulture, University of Kentucky, Lexington, Kentucky 40546, United States
4. Department
of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, United States