1. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China (W.X., W.S.);
2. School of Life Sciences and State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Hong Kong 999777, China (W.X., J.Z.);
3. College of Agronomy, Inner Mongolia Agricultural University, Huhhot 010018, China (L.J.);
4. Institute of Cellular and Molecular Botany, University of Bonn, D-53115 Bonn, Germany (F.B.);
5. Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4 (H.J.K.); and
6. Department of Biology, South University of Science and Technology of China, Shenzhen 518055, China (J.L.)