1. Department of Biochemistry, The University of Arizona, Biosciences West, Tucson, AZ 85721, USA
2. Plant Genetics and Breeding Laboratory, Japan Tobacco Inc., Iwata, Japan
3. Department of Plant Sciences, The University of Arizona, Biosciences West, Tucson, AZ 85721, USA
4. Department of Molecular and Cellular Biology, The University of Arizona, Biosciences West, Tucson, AZ 85721, USA
5. To whom correspondence should be addressed. E‐mail:
6. University of Newcastle, Department of Agricultural and Environmental Sciences, Ridley Building, Newcastle upon Tyne NE1 7RU, UK