1. Biotechnology Research Center, Academy of Agricultural Sciences, Southwest University, Chongqing 400715, P. R. China
2. Department of Biological Sciences, Brock University, St. Catharines, Ontario L2S 3A1, Canada
3. Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611, United States
4. College of Engineering and Technology, Southwest University, Chongqing 400715, P. R. China