School of Statistics, Southwestern University of Finance and Economics, Chengdu, Sichuan 611130, China, Department of Statistics, Iowa State University, Ames, IA 50011, USA, Institute of Tropical Biosciences and Biotechnology (ITBB), Chinese Academy of Tropical Agriculture Sciences (CATAS), Haikou, Hainan 571101, China and Enterprise Institute for Renewable Fuels, Donald Danforth Plant Science Center, St. Louis, MO 63132, USA.