1. Michigan State University Department of Energy Plant Research Laboratory, East Lansing, Michigan 48824-1312
2. Department of Biochemistry, Michigan State University, East Lansing, Michigan, 48824-1312
3. Genetics Program, Michigan State University, East Lansing, Michigan 48824-1312
4. Department of Microbiology, Michigan State University, East Lansing, Michigan 48824-1312