1. State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
2. Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901-8520, U.S.A.