1. State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
2. The Key Laboratory of Biology and Genetic Improvement of Maize in Arid Areas of the Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China
3. Department of Horticulture, Seed Biology Group, College of Agriculture, Food, and Environment, University of Kentucky, Lexington, Kentucky 40546, United States