Funding for this research was provided by:
National Natural Science Foundation of China (11371149, 11701188)
Graduate Student Overseas Study Program from South China Agricultural University (2017LHPY003)
Article History
Received: 21 August 2017
Accepted: 9 May 2018
First Online: 22 May 2018
Competing interests
: The authors declare that they have no competing interests.