6. Funding
This work was supported by the National Key R&D Program, Ministry of Science and Technology, China (Grant No. 2017YFD0300100, 2017YFD0300103 & 2017YFD0300107). This work was also funded by the National Natural Science Foundation of China (Grant No.31701366). We also received support from the Jiangsu Collaborative Innovation Center for Modern Crop Production (JCIC-MCP) and the Fundamental Research Funds for the Central Universities, China (Grant No. KJQN201802).