Acknowledgments
We thank Dr Peter Ryan (CSIRO) for critical reading of the manuscript. We thank Prof. Dongfa Sun of Huazhong Agricultural University for providing Tibetan wild barley accessions. We thank Western Sydney University for providing the SIMS and Confocal Bio-imaging facility. Lijuan Mao and Zhiwei Ge (Zhejiang University) and Linda Westmoreland, Dr Sumedha Dharmaratne, Dr Anya Sali, and David Randall (Western Sydney University) for technical assistance. This work is supported by Natural Science Foundation of China (31771687). S.C is supported by Kuayue Project in Collage of Agriculture and Biotechnology, Zhejiang University. Z.H.C is supported by an Australian Research Council (ARC) Discovery Early Career Researcher Award (DE1401011143) and Horticulture Innovation Australia (VG17003; LP18000).