Acknowledgments
We are thankful to everybody who participated in the studies.

Author Contributions
The manuscript was prepared by S.L., J.Y., Z.Z., and H.Z., and reviewed by the co-authors. All authors have read and agreed to the published version of the manuscript.

Funding
This work was supported by grants from the National Key R&D Program of China (2018YFD0500103 and 2017YFE0204100), the Key Technologies R&D Program of Gansu Province (19ZDNA001) and the Chinese Academy of Agricultural Science and Technology Innovation Project (CAAS-ASTIP-2020-LVRI).

Conflicts of Interest
The authors declare no conflict of interest.