Acknowledgements This study was supported in part by the National Key R&D Program of China (2017YFD0200100, 2017YFD0200104), National Natural Science Foundation of China (Grant No. 31101596, 31372130), Hunan Provincial Recruitment Program of Foreign Experts, and the National Oilseed Rape Production Technology System of China, B2011 Plan^ supported by The Chinese Ministry of Education.