**Supplementary Materials:** Supplementary materials can be found at http://www.mdpi.com/1422-0067/19/12/ 4087/s1.

**Author Contributions:** Z.-S.X. coordinated the project, conceived and designed experiments and edited the manuscript; W.-Y.S. performed the experiments and wrote the first draft of the manuscript; Y.-T.D., J.M. and J.C. conducted the bioinformatic work and performed related experiments; D.-H.M. and L.-G.J. provided analytical tools and analyzed the data; M.C., Y.-B.Z. and X.-H.Z. contributed valuable discussion; and Y.-Z.M. coordinated the project. All authors have read and approved the final manuscript.

**Funding:** This research was financially supported by the National Key R & D Program of China (2016YFD0102000), the National Transgenic Key Project of the Ministry of Agriculture (2018ZX0800909B and 2016ZX08002-002), the National Natural Science Foundation of China (31871624) and the Major Research Development Program of Shaanxi Province (2018NY-026).

**Acknowledgments:** We are grateful to Hui Zhang (Institute of Crop Science, Chinese Academy of Agricultural Sciences) for providing the pCAMBIA3301 vector and pUC57-GmU6-sgRNA.

**Conflicts of Interest:** The authors declare that they have no competing interests.
