A promoter for strong and ubiquitous anaerobic gene expression in tobacco

The maize GapC4 promoter confers strong and ubiquitous anaerobic expression of the beta-glucuronidase reporter gene in transgenic tobacco. Among 21 transgenic tobacco lines harboring 785 or 461 bp from the GapC4 promoter, 18 show anaerobic gene expression, In six lines anaerobic fluorescence values were more than 1000-fold over nonspecific background and in five lines anaerobic gene expression exceeded aerobic expression of a reporter gene construct under the control of the strong cauliflower mosaic virus 35S promoter, Aerobic gene expression was detected in only three lines. Anaerobic induction is observed in all tissues including mature leaves and flowers and is transcriptionally induced within at least 12 h. Within 3 h of transfer of tobacco seedlings from anaerobic to aerobic conditions reporter gene transcription is turned off. Among other environmental factors only wounding and UV light result in a 10- to 40-fold induction of reporter gene expression above background. The strong inducibility, mode of expression under non-inducing conditions, the specificity, and the ubiquitous induction distinguishes the GapC4 promoter from all previously analyzed anaerobic promoter-reporter gene constructs.