COMPARISON OF DIFFERENT CONSTITUTIVE AND INDUCIBLE PROMOTERS FOR THE OVEREXPRESSION OF TRANSGENES IN ARABIDOPSIS-THALIANA

We compared the organ specificity and the strength of different consti tutive (CaMV-35S, CaMV-35Somega, Arabidopsis ubiquitin UBQ1, and barle y leaf thionin BTH6 promoter) and one inducible promoter (soybean heat -shock promoter Gmhsp17.3) in stably transformed Arabidopsis thaliana plants. For this purpose we constructed a set of plant expression vect ors equipped with the different promoters. Using the uidA reporter gen e we could show that the CaMV-35S promoter has the highest expression level which was enhanced two- to threefold by the addition of a transl ational enhancer (TMV omega element) without altering the organ specif icity of the promoter. The barley leaf thionin promoter was almost ina ctive in the majority of lines whereas the ubiquitin promoter exhibite d an intermediate strength. The heat-shock promoter was inducible up t o 18-fold but absolute levels were lower than in the case of the ubiqu itin promoter. Conclusive quantitative results for different organs an d developmental stages were obtained by the analysis of 24 stably tran sformed lines per promoter construct.