XVI International Botanical Congess

The maize GapC4 promoter confers strong and ubiquitous anaerobic expression of the ß-glucuronidase reporter gene in transgenic tobacco and potato. In some tobacco lines anaerobic gene expression exceeds aerobic expression of a reporter gene construct under control of the CaMV 35S promoter. In potato this promoter confers high level anaerobic expression also in tubers. After inoculation of potato tuber discs with the soft-rot pathogen Erwinia carotovora ssp. atroseptica reporter gene expression was detected in the macerated tissue. The promoter was shown to be induced aerobically even in the absence of live bacteria by incubation with purified Erwinia pectolytic enzymes alone. Therefore, promoter induction may also be mediated by a mobile factor. These results demonstrate that the maize GapC4 promoter is suitable for expressing genes encoding antibacterial proteins in transgenic potato.