1. Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology University of Pretoria Pretoria 0002 South Africa
2. Institute for Global Food Security School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens Belfast Northern Ireland BT9 5DL UK
3. Scotland's Rural College Edinburgh EH9 3JG UK
4. Rhizosphere Processes Group Swiss Federal Research Institute WSL Birmensdorf 8903 Switzerland
5. State Key Laboratory of Tibetan Plateau Earth System Science (LATPES) Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS) Beijing 100101 China