1. Institute of Genetics and Physiology, Hebei Academy of Agricultural and Forestry Sciences, Shijiazhuang 050051, P.R. China
2. Plant Genetic Engineering Center of Hebei Province, Shijiazhuang 050051, P.R. China
3. Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, Baoding 071030, P.R. China
4. Department of Gardens, Hebei professional college of political science and law, Shijiazhuang 050061, P.R. China