1. National Citrus Improvement Center, Hunan Agricultural University (Changsha Branch), Changsha 410128, China
2. College of Horticulture, Hunan Agricultural University, Changsha 410128, China
3. College of Plant Protection, Hunan Agricultural University, Changsha 410128, China
4. Department of Agriculture and Food Science, University of Catania, 95123 Catania, Italy