Acknowledgements
The work was supported by grants from the Natural Science Foundation of Gansu Province (17JR5RA146), Special Funds for Discipline Construction of Gansu Agricultural University (GAU-XKJS-2018-096), and Supporting Funds for Youth Mentor of Gansu Agricultural University (GAU-QDFC-2018-07) and Postdoctoral Research Projects (2015GSZYZZ002).
We thank International Science Editing (http://www.internationalscienceediting. com) for editing this manuscript.
The named authors have no conflict of interest, financial or otherwise.