1. College of Forestry, Nanjing Forestry University, Nanjing 210037, China; and Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
2. Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing 210014, China
3. Department of Horticulture, University of Georgia, Athens, GA 30602
4. College of Forestry, Nanjing Forestry University, Nanjing 210037, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China; and Yangzhou Crabapple Horticulture Ltd. Co., Yangzhou 225200, China