Xiong, Xing-yao, Horticulture College, Hunan Agricultural University, Changsha, Hunan, P. R. China; Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan, P. R. China; and Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, P. R. China, China