1. Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences of Nanjing Agricultural University, Nanjing 210095, P. R. China
2. Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing 210014, P. R. China
3. Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing 210095, P. R. China