1. Umeå Plant Science Centre; Department of Forest Genetics and Plant Physiology; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
2. Southern Swedish Forest Research Centre; Swedish University of Agricultural Sciences; 230 53 Alnarp Sweden
3. Biomass and Bioenergy Research Centre; College of Plant Science and Technology; Huazhong Agricultural University; 430070 Wuhan China
4. Key Laboratory of Horticultural Plant Biology of Ministry of Education; College of Horticulture and Forestry; Huazhong Agricultural University; 430070 Wuhan China
5. Umeå Plant Science Centre; Department of Plant Physiology; Umeå University; 901 87 Umeå Sweden