1. Umeå Plant Science Centre; Department of Ecology and Environmental Science; Umeå University; SE-901 87 Umeå Sweden
2. Umeå Plant Science Centre; Department of Plant Physiology; Umeå University; Umeå SE-901 87 Umeå Sweden
3. Department of Plant and Environmental Sciences; Section for Plant Biochemistry; University of Copenhagen; Thorvaldsensvej 40 DK 1871 Frederiksberg Denmark