DIFFERENTIAL ACTIVITY OF THE MANNOPINE SYNTHASE AND THE CAMV 35S PROMOTERS DURING DEVELOPMENT OF TRANSGENIC RAPESEED PLANTS

Fusions of the promoter of the cauliflower mosaic virus 35S RNA transc ript (CaMV 35S) and the mannopine synthase (mas) gene to the beta-gluc uronidase (GUS) reporter gene have been introduced into various cultiv ars of Brussica napus via Agrobacterium-mediated transformation. Trans genic rapeseed plants have been also regenerated from winter cultivars (Santana, Arabella) by shoot induction from kanamycin-resistant callu s tissues on the medium supplemented with AgNO3. Transformation was co nfirmed by Southern hybridization of genomic DNA from primary transfor mants and PCR analysis of DNA from second generation seedlings. beta-g lucuronidase activity analyzed by fluorometric assay or histochemical staining indicated a differential expression pattern for the two promo ters. Organogenesis from in vitro cultured callus tissues was coupled with a relative increase of CaMV 35S promoter activity and reduction o f mas promoter function. In seedlings, the CaMV 35S promoter had maxim um activity in the primary roots, while the mas promoter was the most active in the cotyledons. Etiolated seedlings, cultured in dark, showe d reduced activity of the mas promoter. At rosette stage, both promote rs were more active in elder plant parts than in younger ones. The hig hest activity values were recorded in cotyledons. After bolting, reduc ed promoter Function was detected in upper parts of the transformed pl ants. Histological staining showed that the CaMV 35S promoter was acti ve in the cortex, the phloem and the vascular cambium, while the mas p romoter directed gene expression in the phloem. In conclusion, both pr omoters were found to be functional in majority of the studied organs of transgenic rapeseed plants, however the promoter activity varied co nsiderably between organs and tissues at various developmental stages.