Funding for this research was provided by:
National Nature Science Fund Key Projects (313300630)
China Agriculture Research System (CARS-04-PS13)
Text and Data Mining valid from 2018-05-11
Received: 26 December 2017
Accepted: 30 April 2018
First Online: 11 May 2018
Ethics approval and consent to participate
: Not applicable
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.