Acknowledgements
This study is partially supported by San Diego State University. Financial assistance was partially provided by the SPRUCE and NGEE Arctic projects, which are supported by the Office of Biological and Environmental Research in the Department of Energy Office of Science. This study was partially supported by the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, and the “Top Notch” program in China. C.S. is supported by the National Natural Science Foundation of China (41125001). X.X. acknowledge the financial support from the San Diego State University and the CSU Program for Education & Research in Biotechnology. N.S. was supported by VIDI grant 016.161.318 issued by the Netherlands Organization of Scientific Research.