1. College of Plant Protection, Southwest University, Chongqing 400715, China
2. Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, U.S.A.
3. Citrus Research Institute, Southwest University, Chongqing, 400712, China
4. Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, U.S.A.