1. Plant Physiology/Biochemistry/Molecular Biology Program, Department of Agronomy, Agricultural Sciences Center-North, University of Kentucky, Lexington, Kentucky 40546–0091 (Y.H., H.F., D.F.H., S.G.); and the
2. Tobacco and Health Research Institute, University of Kentucky, Lexington, Kentucky 40546–0236 (Y.H., S.G.)