Naiman Desertification Research Station;
Cold and Arid Regions of Environmental and Engineering Research Institute;
Chi- nese Academy of Sciences;
Lanzhou 730000;
China;
Laboratory of Plant Stress Ecophysiology and Biotechnology;
CAREERI;
Chinese Academy of Sciences;
Lanzhou 730000;
China;
Key Laboratory of Arid and Grassland Ecology of Ministry of Education;
Lanzhou University;
Lanzhou 730000;
China;
School of Biological Sciences;
University of Nebraska-Lincoln;
Lincoln 62588;
USA;